A_new_tetrapod_ichnotaxon_from_Botucatu

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F
ss
Luciana Bueno dos Reis Fernandes , Marcelo Adorna Fernandes
a Programa de Pós Graduação em Ecologia e Recursos Natur
Brazil
b Universidade Federal de Pernambuco, campus Vitória de S
c Laboratório de Paleoecologia e Paleoicnologia, Departamen
Carlos, São Paulo, Brazil
a r t i c l e i n f o
ity when hunting, escaping predators, or to facilitate progression on inclined planes and hot sand. São Bento quarry
d mammaliform foot-
ds trails and burrows
des et al., 2004). Coni-
rtion of Minas Gerais
fossils are rare and
Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
Contents lists available at ScienceDirect
Palaeogeography, Palaeocli
j ourna l homepage: www.e ls
paleoerg deposited during the Early Cretaceous (Neocomian) (Renne
et al., 1992; Turner et al., 1994). Among Botucatu Formation trace fossils
paleovertebrate bone descriptions are absent to date.
Due to the rarity of body fossil, paleobiological and paleoecological
details of the Botucatu Formation can only be accessed throughout
1. Introduction
Botucatu Formation is an aeolian geological unit known worldwide
for its ichnofossils. Its fossil record comprises mainly bioturbation pro-
duced by vertebrates and invertebrates, which lived in an immense
are theropod and ornithopod tracks, small-size
prints (Brasilichnium isp.), insects and arachni
(Leonardi et al., 2007), as well as urolites (Fernan
fer logs have been recorded in the northern po
State (Pires et al., 2011), nevertheless, body
represents a paleodesert environmentwith relative highhumidity,where temporary lagoonsmayhave formeddur-
ingpluvial events. Paleo-rain episode evidence is preserved through raindrops impact craters on local sandstone. São
Bento quarry paleoenvironment sustained a rich paleofauna, represented by abundant ichnofossils. This local diver-
sity suggests a punctual productive desert paleocommunity with several paleoecological interactions, where
Brasilichnium producer was one of the fundamental elements.
© 2016 Elsevier B.V. All rights reserved.
⁎ Corresponding author.
E-mail addresses: pedro.buck@hotmail.com (P.V. Buck
(A.M. Ghilardi), b.peixoto@protonmail.ch (B. de C. P. e M.
lucianabrfernandes@google.com (L.B.R. Fernandes), marce
(M.A. Fernandes).
http://dx.doi.org/10.1016/j.palaeo.2016.11.009
0031-0182/© 2016 Elsevier B.V. All rights reserved.
plained by total overlap of pes and manus impression and subsurface hand impression. Comparing with recent or-
ganisms living in similar environments and conditions, the Botucatu Formation B. saltatorium producer should have
been a generalist organism likelywith an omnivorous habit. It may have adopted hopping locomotion to gain veloc-
Brasilichnium saltatorium isp. nov.
Mammaliform footprints
Saltatorial locomotion
Ichnofossil
Paraná Basin
Paleodesert
ais, Centro de Ciências Biológicas e da Saúde, UFSCar, Rodovia Washington Luís, km 235 - SP-310, 13565-905 São Carlos, São Paulo,
anto Antão, Pernambuco, Brazil
to de Ecologia e Biologia Evolutiva, Universidade Federal de São Carlos, Rodovia Washington Luís, km 235 - SP-310, 13565-905 São
a b s t r a c t
Botucatu Formation is a paleoerg, worldwide famous for its vertebrate and invertebrate ichnofossils. Among
Botucatu Formation tetrapod tracks, ichnogenus Brasilichnium Leonardi, 1981 is well known, being generally attrib-
uted to mammaliform trackmakers. In this study a new ichnotaxon is described, Brasilichnium saltatorium isp. nov.,
characterized by a hopping locomotion in phases. The new ichnotaxondiffers from B. elusivum Leonardi, 1981main-
ly for the locomotion pattern. It also differs from other ichnotaxa by indicating hopping progression regarding limb
morphology and track configuration. Fossil evidence shows B. saltatorium and B. elusivum could be produced by the
same organism and represent an alternation in locomotory behavior. Neoichnological experiments were conducted
to better understand track preservation and aspects of saltatorial dynamics on inclined planes. It was observed dif-
ferences in heteropody degree may be related to movement direction and locomotion effort on ascending or de-
scending the incluned plane. Due to extramorphological features, heteropody is more evident when the producer
climbs the simulated dune. Also, when the movement is ascendent, lack of handprints can occur. This can be ex-
Article history:
Received 11 July 2016
Received in revised form 28 October 2016
Accepted 5 November 2016
Available online 11 November 2016
Keywords:
Pedro Victor Buck a,⁎, Aline Marcele
c
Ghilardi b, Bernardo de C. P. e M. Peixoto a,
c
A new tetrapod ichnotaxon from Botucatu
(Neocomian), Brazil, with comments on fo
inclined planes and local paleoecology
), alinemghilardi@yahoo.com.br
Peixoto),
licno@yahoo.com.br
ormation, Lower Cretaceous
il track preservation on
matology, Palaeoecology
ev ie r .com/ locate /pa laeo
ichnofossil and other sedimentary structures analysis. Regarding this,
Araraquara and São Carlos region, São Paulo state, is of great impor-
tance, since it constitutes one of the biggest Botucatu Formation
ichnofossil diversity hotspots (Leonardi and Carvalho, 2002). The region
is also of historical relevance since thefirst trace fossils of South America
- assigned to tetrapods by Huene (1931) -were discovered in São Carlos
by the mining engineer Joviano A. A. Pacheco in 1911 (Pacheco, 1913).
Among the various studies conducted in Araraquara and São Carlos
area, those of Giuseppe Leonardi have great relevance. This researcher
is one of the pioneers in detailed interpretations of Botucatu Formation
ichnofossils and is responsible for ichnogenus Brasilichnium original de-
scription (Leonardi, 1981).
Among Botucatu Formation tetrapod tracks, ichnogenus Brasilichnium
is highlighted because it may represent the only mammaliform record
from the Lower Cretaceous of Brazil. Besides occurring in the Botucatu
Formation,Brasilichnium is also described in aeolian deposits of the north-
eastern U.S.A. (Lockley and Hunt, 1995) and in the Twyfelfontein Forma-
tion in Namíbia. Twyfelfontein Formation has already been correlated
with Botucatu Formation and suggests paleogeographic continuity of
Botucatu desert in the African portion of Gondwana (Porchetti and
Wagensommer, 2015).
For the ichnospecies B. elusivum, morphotype variation regarding
presence or absence of hand impressions has already been described.
This variation of handprint preservation was attributed to an artifact of
preservation (Lockley, 2011). However, other morphotypes associated
to Brasilichnium also occur. They are rarer, have not yet been described
in literature, and instead of being related to preservational features, they
are associated with variation in the producer's locomotory behavior. The
observed configuration of this hitherto undescribedmorphotype suggests
an asymmetrical hopping gait, different from the cursorial progression
typical of B. elusivum. The present paper aims to describe and interpret
this different morphotype, controlled by behavior, and determine a new
several countries in South America such as Brazil, Paraguay, Argentina
and Uruguay, and reaches a total thickness of 7000 m of sedimentary
and igneous rocks (Milani et al., 2007).
Botucatu Formation is part of the Gondwana III Paraná Basin super se-
quence and is comprised of aeolian facies of fine tomedium-grained well
sorted quartzose sandstones. It is characterized as an immense paleoerg
with medium to large cross-bedding, deposited in a continental context
under the influence of strong monsoon winds from the N and SW
(Scherer and Goldberg, 2007). The Botucatu Formation has an estimated
area of 1,300,000 km2 and covers the Brazilian states of São Paulo, Mato
Grosso, Mato Grosso do Sul, Goiás, Minas Gerais and Rio Grande do Sul.
Chronocorrelated units also occur in Uruguay, Paraguay, and Namíbia.
InSão Paulo state, Botucatu Formation occurs in an NE-SW belt and
appears inmany hinterlandmunicipalities. However, themain outcrops
are located in Araraquara and São Carlos region (Fig. 1). One of the larg-
est exploration sites of Botucatu sandstone was São Bento quarry. This
locality is nowadays disused and is located in Araraquara municipality
(21°49′03.4″S and 48°04′22.9″W). All material analyzed in the present
work was collected in this area. São Bento quarry consists of a 20 m
high and 100 m long paleodune, displaying its foresets, which have an
average of 29° dip in S-SW direction (Fig. 2).
The many decades of sandstone exploitation for commercial pur-
poses (i.e. public and private paving) allowed the rescue of hundreds
of slabs containing ichnofossils and other relevant sedimentary struc-
tures. Before 1997, Giuseppe Leonardi employed the largest effort to
collect and recue slabs from the Botucatu Formation. Between 1997
and 2006, the authors M. A. Fernandes and L. B. R. Fernandes collected
22 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
ichnotaxon covering its variations. Neoichnological experiments were
also conducted to better understand track preservation and aspects of
hopping dynamics on inclined planes. Finally, some comments on the pa-
leoecology of Botucatu Formation are made.
2. Material and methods
2.1. Geological context
Paraná Basin has an oval shape stretched in north-south directions
and covers an area of approximately 1,500,000 km2. It encompassed
Fig. 1. Location of the Paraná Basin showing the area of occurrence of the Botucat
a vast amount of slabs during weekly visits to São Bento quarry.
This material is deposited in the Laboratório de Paleoecologia e
Paleoicnologia (LPP) of the Universidade Federal de São Carlos
(UFSCar). The slabs with ichnofossils were generally found already re-
moved from their original stratigraphic context, grouped into batches
ready to be shipped to market.
The Botucatu Formation paleoenvironment was similar to current
hot sandy deserts. Its landscape consisted of an extensive field of medi-
um to large aeolian duneswith interdune valleys (Talbot, 1985). The cli-
mate during its deposition was arid and may have been extremely hot
and dry (Nowatzki and Kern, 2000). Nevertheless, due to the large
u Formation in São Paulo State, Brazil. Adapted from Fernandes et al. (2011).
extent of Botucatu desert, various climatic regimes could have influ-
enced different areas. A way from the desert's innermost part, wetter
climates could have occurred (Talbot, 1985). The Araraquara region,
for example, was possibly located at the desert border. The abundant
ichnofauna and several non-biogenic sedimentary structures (Fig. 3) in-
dicate the presence of moisture and water available during deposition.
Fig. 2. São Bento quarry, Araraquara - SP. A. panoramic view, January 2016; B–C, dune deposit characteristic of Botucatu Formation, April 2004; C.white segmented rectangle indicates the
surface where LPP-IC-0001 (holotype) was collected.
23P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
Fig. 3. Non-biogenic sedimentary structures indicating the presence of moisture and water av
impressions; C. adhesion ripples; D. contraction cracks. All samples were collected in São Bent
ailable during the deposition of Botucatu Formation in Araraquara region. A–B. raindrop
o quarry. Scales in centimeters.
The raindrop impressions seen in Fig. 3 (A and B) suggest the occur-
rence of pluvial events. Rain makes the sand wet and adherent, there-
fore, the adhesion ripples showed in Fig. 3C may also be related to
rainfall episodes. After the rainfall, the wet layers of sand get covered
by new dry sand layers, forming typical adhesion structures.
After rainfall episodes, part of themeteoric water could also have ac-
cumulated in interdune depressions forming ephemeral lagoons. When
these lagoons dried, contraction cracks like those showed in Fig. 3Dmay
have formed. Another part of the rain water could have seeped through
the sand, contributing to the increase of moisture in the subsurface and
to raise the groundwater level.
In addition to the above-cited structures, the abundance of trace fos-
sils found in the same area is remarkable. This is also indicative of a
higher level of moisture in the local environment, otherwise, footprints
preservation and even the animal survival itself in the past would not
have been possible (McKeever, 1991).
The age for the Botucatu Formation is estimated at 132Ma by Renne
et al. (1992) through Ar40/Ar39 based on the Serra Geral Formation ba-
salt. The Serra Geral Formation overlies the Botucatu Formation. Its ori-
gin is related to the rupture of the supercontinent Gondwana and the
24 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
opening of South Atlantic Ocean. Serra Geral lava flows advanced over
the Botucatu desert, covering the dunes and providing its preservation.
The contact of these formations is not considered to bediscordant and in
certain places the Botucatu sandstone is found intermingled with the
Serra Geral basalts indicating the prevalence of arid conditions during
themagmatic event (Scherer, 2002). Turner et al. (1994) propose an in-
terval for the Serra Geral eruptions between 137 and 127Ma.Inferences
about the early Botucatu desert deposition are up for debate. Scherer
(2000) estimates the desert was deposited in a short period of time in
the range of hundreds of thousands of years. This author concluded
this based on the tickness of the Botucatu Formation, the lack of any pre-
served supersurface within the aeolian succession and the conformable
higher contact with the Serra Geral Formation. Scherer (2000) infers a
Neocomian age for Botucatu Formation (Fig. 4), while Bonaparte
(1996) adopts an age between the Jurassic-Cretaceous transition, solely
on the basis of vertebrate trace fossils.
2.2. Neoichnology
While trace fossils are the object of interest of paleoichnology, struc-
tures produced by living organisms are studied by a related science,
neoichnology. The interaction between these two sciences allows a bet-
ter interpretation of the ichnofossil record. Though neoichnology, hy-
potheses can be tested using experimentation. For example,
footprints, tracks, and other biogenic structures can be produced in
Fig. 4. Botucatu Formation stratigraphy for Brazilian territory (adapted from Francischini
et al., 2015).
controlled conditions, and then, compared with trace fossils. Based on
the work of Brand (1996), Davis et al. (2007) and Milàn and Bromley
(2008), for example, Neoichnology proves to be a useful tool in resolv-
ing ichnotaxonomical, preservational and paleoenvironmental issues.
Ultimately, neoichnology provides the means to investigate the pro-
cesses involved in ichnites production.
In the current study, we sought to use neoichnology to understand
ichnogenus Brasilichnium variation and saltatorial dynamics on inclined
planes. Tracks assigned to Brasilichnium occur in upward and down-
ward directions relative to the paleodune. Due to this, they may show
different morphologies and locomotory parameters, such as variation
in the heteropody and differences in the jump length.
For the neoichnogical experiment,Meriones unguiculatus (Rodentia,
Muridae), a small domesticated rodent popularly know as Mongolian
gerbil, was used. The choice is justified by the hopping locomotion typ-
ical of this animal. The weight of the individual used was 54.9 g and its
length (i.e. measure from of the base of the tail to the tip of the snout)
was 10.48 cm. Both hands and feet of Meriones unguiculatus have five
digits.
The organismwas placed towalk on a sandy surface inside awooden
box of 1.2 m long and 1.1 m wide. The box size allowed the animal to
move withoutmajor restrictions. The sand used in the experiment
was courtesy of Mineiração Itaporanga Ltda., which excavates sand
from the weathering Botucatu sandstone. The sand moisture used was
1.1%, enough to keep the footprints morphology during track
registration.
The experiment consisted of producing tracks on a horizontal plane
and on an inclined plane of 25°, in order to simulate the slope of the
paleodune. Morphological and locomotory parameters were then com-
pared between three treatments: 1)when the animalmoved in the hor-
izontal plane; 2) when it climbd the simulated dune; and 3) when it
descended it. Finally, the results were compared with Brasilichnium sal-
tatorial fossil tracks.
After being positioned at one end of the box, the animal's natural ex-
ploratory behavior allowed tracks to be produced. One result of each ex-
periment was measured and considered in the analysis.
2.3. Ichnological description
The convention proposed by Leonardi (1987) was used for morpho-
logical description. Pes and manus length, width, length/width ratio,
stride length, oblique pace, and, in some cases, pace angulation were
measured, as well as the distance between manus and pes sets. Param-
etersmeasured for the description herein are shown in Fig. 5.We calcu-
lated the mean and standard deviation of each parameter in order to
allow the comparison between the tracks. The holotype and 1st
paratype of Brasilichnium elusivum, deposited in the collection of the
Museu Nacional (Rio de Janeiro, Brazil), were also measured. One-way
ANOVA (Tukey) Statistical Analyzes and Student's t-test were applied
to the measurements in order to determine similarities and differences
between the trackways.
The software ImageJ was used formeasuringmorphological features
and InStat3 was used to perform statistical analysis. Both Softwares are
freely available.
3. Results
3.1. Neoichnology
Descriptive parameters of the tracks produced by the three different
treatments are summarized in Table 1, and can be seen in Fig. 6.
Regarding the footprint descriptive parameters, pes length showed
the highest variation between the three experiments (coefficient of var-
iability: 20.05%). Pes length was significantly larger when the animal
descended the inclined plane. ANOVA analysis considered pes length
statistically different among all experiments (P b 0.05). Manus length
25P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
also varied, but to a lesser extent. ANOVA showed statistically signifi-
cant differences in manus length between all experiments (P b 0.05),
except among the horizontal and ascending ones.
The width of both pes and manus showed the lowest variation
(9.6% and 13.89%, respectively) among the experiments. The mea-
sures were slightly larger when the animal descended the inclined
plane. The width of pes was statistically different only between the
ascending and descending experiments (P b 0.05). The width of
manus was statistically different between the ascending and de-
scending experiments, as well as in the descending and horizontal
experiments (P b 0.05).
Fig. 5.Morphological and locomotorial parameters measured for (A) cursorial and (B) saltator
HMD: horizontal inter-manus distance; VMD: vertical inter-manus distance; DMP: distance be
Table 1
Descriptive parameters ofMeriones unguiculatus trackways. Means are presented followed by
Descendant Ascend
Pes
Length (L) 3,01 ± 0,32 1,99 ±
Width (W) 1,59 ± 0,15 1,39 ±
L/W ratio 1,9 ± 0,17 1,45 ±
External width 4,43 ± 0,21 4,43 ±
Hop 14,8 ± 0,92 14,5 ±
Manus
Length (L) 1,55 ± 0,18 1,36 ±
Width (W) 1,12 ± 0,05 0,89 ±
L/W ratio 1,38 ± 0,1 1,53 ±
External width 2,62 ± 0,14 2,59 ±
Hop 14,5 ± 1,26 14,58 ±
DMP 1,05 ± 0,85 0,11 ±
The average length of pes impressions produced in the descending
experiment is 33.88% and 19.27% higher than those produced in the as-
cending and horizontal experiments respectively. The width of pes im-
pressions showed less variation, being 12.57% and 8.8% higher in the
descending experiment when compared with the ascending and hori-
zontal experiments respectively. It was already expected descending
experiment autopodia measurements were larger. This is explained by
aspects of movement dynamics. When the organism descends the in-
clined plane, a higher speed can be obtained, increasing the autopodia
drag and sand displacement. This feature is observed because in the de-
scendingmovement, and also in the horizontal plane, the organismuses
ial locomotion. HPD: horizontal inter-pedes distance; VPD: vertical inter-pedes distance;
tween manus and pes.
standard deviations (in cm). DMP: distance between manus and pes.
ant Horizontal Total coefficient of variability (%)
0,13 2,43 ± 0,12 20,05
0,12 1,45 ± 0,06 9,6
0,29 1,67 ± 0,08 16,25
0,29 4,5 ± 0,24 5,22
0,6 11,45 ± 1,73 15,99
0,9 1,35 ± 0,13 11,76
0,06 0,88 ± 0,09 13,89
0,16 1,54 0,25 13,1
0,16 2,23 ± 0,34 11,79
2,29 11,78 ± 1,1 14,79
0,12 0 172,31
3.2. Systematic paleoichnology
Ichnofamily Chelichnopodidae Lockley, 2011
Diagnosis Lockley, 2011
Tetrapod trackways with mammal-like (synapsid) characteristics:
complete manus and pes impressions rounded to transversally oval
with manus slightly or significantly smaller than pes, showing the gen-
eral pattern of a quadruped. Manus and pes with transversaly oval heel
pad and up to five short digit traces, but often with only three or four
impressed. Trackway width, pace angulation and pes and manus rota-
tion variable.
Included ichnogenera: Chelichnus, Jardine, 1850 and Brasilichnium
Leonardi, 1981.
Icnogenus Brasilichnium Leonardi, 1981 (See Figs. 7 A,B and Table 2
for descriptive parameters.)
Revised diagnosis Fernandes and Carvalho, 2008
Quadruped trackway, with small dimensions; mean gleno-acetabu-
lar distance of 7.5 cm. Manus significantly smaller than the pes; manus-
pes distance increases when the walking speed decreases. Pace angula-
tion is relatively high for a quadruped. Heteropody is directly propor-
tional to the pes longitudinal axis positive rotation (values N75°). Pes
with the longitudinal axis parallel to the trackway axis and with pace
angulation N125° do not show heteropody. Pes impressions are ellipti-
26 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
Fig. 6. Tracks produced byMeriones unguiculatus in three different experiments. In each
experiment, five sets of pes and manus are disclosed. A. Descending; B. Ascending; C.
Horizontal. Direction of movement towards the top of the picture. Scales in centimeters.
more of its hind limb for support, forming a larger footprint on the lon-
gitudinal axis (i.e. extramorphological variation). When ascending the
inclined plane, this behavior is not observed, and the pes impressions
are smaller and/or less visible.
It was noted that the length/width ratio (L/W ratio) increases due to
the autopodia extramorphology. This can skew interpretations about
the potential trackmaker. As expected, the pes L/W ratio is statistically
different (P b 0.001) between the descending and ascending experi-
ments. In the ascending movement, the hind limb support is less ex-
pressive. The manus L/W ratio showed no statistical difference
between the experiments. This indicates the hands may play a subsidi-
ary support in the animal locomotion, causing less interference in the
manus morphology across different locomotory situations.
Among all the parameters analyzed, the greatest variation was ob-
served in the distance between pes/manus sets (coefficient of variabili-
ty: 172.31%). The pes andmanus partially overlapwhen the organism is
climbing the inclined plane and also when it is moving around in the
horizontal plane. While descending the simulated dune, overlapping is
observed only in the first set of footprints, when the organism is begin-
ning themovement. Regarding pes/manus sets distance, the only mea-
sures not considered statistically different from each other were the
ones of the ascending and horizontal treatments. The hand impressions
notably surpass the pes in the descending experiment because of the
easiest movement impulse, due to gravity. In the ascending and hori-
zontal plane experiments, the distance between manus and pes sets
shortens or is even zero.
The external width of manus and pes sets and the hop distancewere
only statistically different between the descending and horizontal ex-
periments. One should expect that an increase in locomotorial effort
would result in a smaller hop, as observed in the results of Brand
(1996). However, this parameter is probably controlled by behavior.
The trackway produced would be greatly dependent on the energy
employed by the animal at the time of movement.
cal with transversal axis almost larger and anteroposterior axis slightly
directed inwards; short toes, generally rounded,with prossible 2-3-3-3-
3 phalangeal formula; the posterior autopodium is ectaxonic and
tetradactyl (digits II, III, IV and V) in semi plantigrade condition. There
is a greater hypex digit in slight abduction. Anterior autopodium has
at least four digits with nails; nails may be apparent or not, by virtue
of preservation. Tail impressions/drag are always absent.
Type ichnospecies: Brasilichnium elusivum Leonardi, 1981.
Included ichnospecies: Brasilichinium elusivum Leonardi, 1981 and
Brasilichnium saltatorium isp. nov.
Ichnospecies Brasilichnium saltatorium isp. nov., Fig. 8.
Referred material
Holotype: LPP-IC-0001, LPP-IC-0002. Paratypes: LPP-IC-0003, LPP-IC-
0004, LPP-IC-0005, LPP-IC-0006, LPP-IC-0007, LPP-IC-0008, LPP-IC-0009,
LPP-IC-0010, LPP-IC-0011, LPP-IC-0012, LPP-IC-0013, LPP-IC-0014.
Locality
São Bento Group, Botucatu Formation, São Bento quarry, Araraquara
municipality, São Paulo state, Brazil. Geographic coordinates: 21°49′
03.4″S e 48°04′22.9″W.
Fig. 7. Slabs containing Brasilichnium elusivum tracks. A. holotype MNRJ 3902-V; B. 1st
Paratype MNRJ 3903-V. Scales in centimeters. Direction of movement towards the right
of the picture.
Horizon
Holotype LPP-IC-0001 was collected in the basal portion of the
paleodune, approximately 1.5 m above ground level and with a 20°
dip S-SW.
Association
In the same slab of the holotype one theropod track going in the op-
posite direction can be observed. Invertebrate trails are also preserved
near the first set of handprints.
Repository
Trace fossils collection of the Laboratório de Paleoecologia e
Paleoicnologia (LPP), Departamento de Ecologia e Biologia Evolutiva
Diagnosis
Quadruped trackway, with small dimensions and hopping locomo-
tion in phases. Pes impression rounded to transversally oval; manus,
when present, usually elongated in the anteroposterior axis due to the
animal's displacement; heteropody not so evident due to preservational
aspects related to the direction of movement. When the track is de-
scending the inclined plane, manus and pes sets are more evident;
when the trail goes upwards the inclined plane, manus sets are unclear.
The pes surpasses the manus during the movement cycle. Pes are hori-
zontally aligned in a subparallel way and are laterally spaced;manus are
vertically aligned and laterally spaced, minimally apart from the track-
way midline; taking the trackway midline as a reference, the right pes
andmanus are posteriorly located to their left counterpart. Hindfoot im-
pressions are tetradactyl (digits II, III, IV and V), andwhen digits are vis-
ible, it presents a mesaxonic condition; digits III and IV are longer in
relation to the others. Tail impressions/drag are always absent.
Description
Descriptive parameters of Brasilichnium saltatorium isp. nov. holo-
type and paratypes are summarized in Table 3.The paratypes can be
seen in Figs. 9 and 10.
Twelve trackways indicating the hopping gait were analyzed. Re-
garding the direction of movement, the holotype LPP-IC-0001 (Fig. 8),
LPP-IC-0003, LPP-IC-0004 and LPP-IC-0005 (Fig. 9 A, B and D) are in a
downward direction relative to the inclined plane. Four different lines
of evidence reinforce this interpretation: (1) the dynamics of the salta-
torial quadrupedal movement, where the jump momentum is per-
formed by the hindlimbs; (2) the sand arcs formation in the anterior
part of the footprints; (3) the pedes subparallel position, where the
right feet impression is slightly behind its left counterpart (in most
specimens); (4) the possible impression of digits in the fifth and sixth
re fo
ista
Table 2
Descriptive parameters of Brasilichnium elusivum MNRJ 3902-V (holotype) and MNRJ
3903-V (1st paratype). Means are presented followed by standard deviations (in cm).
DMP: distance between manus and pes.
MNRJ 3902-V MNRJ 3903-V
Pes
Length 2,03 ± 0,14 2,23 ± 0,12
Width 2,76 ± 0,14 2,7 ± 0,12
L/W ratio 0,73 ± 0,04 0,82 ± 0,04
Oblique pace 5,94 ± 0,79 6,88 ± 0,21
Stride length 9,54 ± 2,24 11,83 ± 0,42
External width 6,5 ± 0,62 6,27 ± 0,35
Pace angle 107,35 ± 24,09 118 ± 2,62
Manus
Length 0,88 ± 0,25 –
Width 0,98 ± 0,3 –
L/W ratio 0,88 ± 0,1 –
Oblique pace 6,29 ± 0.95 –
Stride length 10 ± 1,96 –
Pace angle 103, 46 ± 13,23 –
DMP 3,35 ± 1,41 –
27P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
(DEBE), Universidade Federal de São Carlos (UFSCar), São Carlosmunic-
ipality, São Paulo State, Brazil.
Etimology
The specific name refers to the saltatorial mode of locomotion ob-
served in the new ichnotaxon.
Table 3
Descritive parameters ofBrasilichnium saltatorium isp. nov. holotype andparatypes.Means a
inter-pedes distance; HMD: horizontal inter-manus distance; VMD: vertical inter-manus d
LPP-IC-0001 LPP-IC-0003
Pes
Length (L) 2,16 ± 0,16 2,09 ± 0,15
Width (W) 2,25 ± 0,16 2,4 ± 0,18
L/W ratio 0,96 ± 0,13 0,087 ± 0,04
External width 7,86 ± 0,43 7,47 ± 0,38
Hop 28,05 ± 0,61 30,15 ± 0,07
HPD 5,6 ± 0,44 4,81 ± 0,29
VPD 1,32 ± 0,42 0,32 ± 0,32
Manus
Length (L) 2,2 ± 0,37 –
Width (W) 1,68 + 0,2 –
L/W ratio 1,31 ± 0,18 –
External width 3,76 ± 0,51 –
HMD 1,97 ± 0,34 –
VMD 4,67 ± 0,25 –
DMP 4,36 ± 0,77 5,3 ± 0,61
LPP-IC-0008 LPP-IC-0009
Pes
Length (L) 1,57 ± 0,08 2,01 ± 0,12
Width (W) 1,76 ± 0,12 2,31 ± 0,16
L/W ratio 0,89 ± 0,02 0,87 ± 0,07
External width 3,87 ± 0,56 7,1 ± 0,13
Hop 16,84 ± 2,29 16,77 ± 0,46
HPD 2,15 ± 0,36 4,79 ± 0,15
VPD 0,68 ± 0,2 0,85 ± 0,44
Manus
Length (L) – –
Width (W) – –
L/W ratio – –
External width – –
HMD – –
VMD – –
DMP – –
hindfoot impression of LPP-ICC-0001 and LPP-ICC-003, respectively,
and the clear digit marks in LPP-ICC-0004 pointing in the direction of
movement.
The tracks preserved as concave epirelief mostly without sediment
filling the footprints cavities, are as follows: LPP-IC-0001, LPP-IC-0008,
llowedby standarddeviations (in cm).HPD: horizontal inter-pedes distance; VPD: vertical
nce; DMP: distance between manus and pes.
LPP-IC-0004 LPP-IC-0005 LPP-IC-0006 LPP-IC-0007
3,49 ± 0,27 2,34 ± 0,04 1,46 ± 0,16 1,46 ± 0,06
2,43 ± 0,12 2,3 ± 0,07 1,78 ± 0,26 1,73 ± 0,04
1,43 ± 0,13 1,02 ± 0,05 0,82 ± 0,06 0,84 ± 0,03
6,21 ± 0,09 7,3 4,35 ± 0,52 3,59 ± 0,32
41,02 – 10,58 ± 0,2 15,39 ± 4,53
3,76 ± 0,14 5,29 3,19 ± 0,31 2,2 ± 0,01
0,66 ± 0,07 1,62 0,47 ± 0,24 3,69 ± 0,66
– 2,11 ± 0,09 – –
– 2,45 ± 0,01 – –
– 0,86 ± 0,03 – –
– 4,33 – –
– 2,2 – –
– 3,4 – –
3,76 ± 0,14 4,42 – –
LPP-IC-0011 LPP-IC-0012 LPP-IC-0013 LPP-IC-0014
1,89 ± 0,08 1,64 ± 0,16 2,32 ± 0,2 1,89 ± 0,29
1,85 ± 0,05 1,99 ± 0,18 2,35 ± 0,08 2,16 ± 0,18
1 ± 0,05 0,82 ± 0,04 0,98 ± 0,09 0,87 ± 0,08
5,83 5,16 ± 0,63 7,54 ± 0,23 7,55 ± 0,11
14,32 20,52 ± 2,31 14,29 ± 0,28 13,41 ± 0,16
3,73 2,77 ± 0,4 5,18 ± 0,24 5,21 ± 0,01
1,28 1,71 ± 0,52 0,33 ± 0,24 0,29 ± 0,04
– – – –
– – – –
– – – –
– – – –
– – – –
– – – –
– – – –
28P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
LPP-IC-0009, LPP-IC-0011, LPP-IC-0012, LPP-IC-0013 and LPP-IC-0014.
Some prints of the holotype (LPP-IC-0001) and LPP-IC-0013 however,
still have sediment infill. The only ones with mold and cast are LPP-IC-
0001 (LPP-IC-0002; sets two-five) and LPP-IC-0009 (LPP-IC-0010; five
sets). Trackways LPP-IC-0003, LPP-IC-0004, LPP-IC-0005, LPP-IC-0006
and LPP-IC-0007 are preserved as convex hyporelief. LPP-IC-0004
(Fig. 10A) can safely be recognized as an undertrack, as the impressions
contours are difficult to define, when compared with the Brasilichnium
elusivum footprints observed in the same slab.
Five sets of manus and pes can be recognized in the LPP-IC-0001
(holotype). They represent four cycles of movement. The movement
start with the feet impressedon the substrate giving the impulse to
the jump. After the jump, the hands landed on the substrate and were
passed by the feet, which left footprints right in front of the handprints
at the same time these were formed. The cycle is ended, and a new one
began. This characterizes the saltatorial movement in phases. In this
Fig. 8.Brasilichnium saltatorium isp. nov. holotype, LPP-IC-0001. A. overview; B–F. set 1 to 5 ofma
in centimeters. The arrow indicates the direction of movement.
kind of locomotion, the front autopodia touch the substrate substantial-
ly simultaneously, and, in the following moment, the rear autopodia
also imprinted the substrate. Ultimately, this is recognized as an
asymmetrical locomotion (Abourachid, 2003). The trackway LPP-IC-
0005 (Fig. 9D) has a single set of manus and pedes, representing only
one moment of surpassed limbs, not being possible measure the hop
distance.
Due to the type of movement in phases, the pace angulation and
oblique pace were not considered. The average hop distance in LPP-IC-
0001 (holotype) is 28.05 ± 0.61 cm. The horizontal and vertical inter-
pedes distance in relation to the midline in the same specimen is
5.6 ± 0.44 and 1.32 ± 0.42 cm, respectively; while, the horizontal and
vertical inter-manus distance is 1.97±0.34 and 4.67±0.25 cm, respec-
tively. The largest hop distance can be seen in LPP-IC-0004 trackway
(Fig. 9B), with a single value of 41.2 cm. The smallest hops were ob-
served in LPP-IC-0006 (Fig. 9F), with average 10,58 ± 0,2 cm. The
nus and pes. They represent the sets inwhich thepes appears anterior to themanus. Scales
29P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
greater hop distances were recorded in the trackways in which the
movement direction is downward the paleodune.
The horizontal inter-pedes distance (HPD) does not seem to have
any relation to the direction of movement (upwards/downwards), but
rather it correlates with the posture adopted by the animal and its
size. The lowest HPD values are for LPP-IC-0007 (2,2 ± 0,01) (Fig.
10C) and LPP-IC-0008 (2,15 ± 0,36) (Fig. 10B), which have lower pro-
portions when compared between other trackways. In the trackways
in which the movement was downward the paleodune, pes width are
similar (holotype LPP-IC-0001: 2,25 ± 0,16; LPP-IC-0003: 2,4 ± 0,18;
Fig. 9. Paratypes of Brasilichnium saltatorium isp. nov. A. LPP-IC-0003. B; LPP-IC-0004; C. LPP-I
Scales in centimeters. Direction of movement towards the top of the picture.
LPP-IC-0004: 2,43 ± 0,12; LPP-IC-0005: 2,3 ± 0,07), indicating a possi-
ble similar size between trackmakers. However, LPP-IC-0001 and LPP-
IC-0003 showed statistically different HPD values (P b 0.05). LPP-IC-
0013 (2,35±0,08) and LPP-IC-0014 (2,16±0,18) have peswidths sim-
ilar to the holotype, but the direction of movement is upwards. They
showed no statistical difference in the HPD parameter (P N 0, 05), rein-
forcing this idea. Based on the statistical results, the same principle can
be applied to the vertical inter-pedes distance (VPD).
With respect to the autopodia morphology, the feet impressions are
wider but less long than the handprints. The holotype (LPP-IC-0001)
C-0009; D. LPP-IC-0005; E. LPP-IC-0011; F. LPP-IC-0006; G. LPP-IC-0013; H. LPP-IC-0014.
. LP
30 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
pes and manus L/W ratio are 0.96 ± 0.13 cm, and 1.31 ± 0.18 cm, re-
spectively. This is most likely due to the autopodia interaction with
the substrate in the landing movement dynamics. When the autopodia
made contact with the substrate, the jump speed and power provided a
greater drag. The greatest pes and manus L/W ratio is observed in LPP-
IC-0004 trackway (1.43 ± 0.13 cm). This is possibly explained by the
extra dragging produced by the autopodia during the downwardmove-
ment in the inclined plane.
In the LPP-IC-0004 (Fig. 11C) and LPP-IC-011 (Fig. 11D–E) tracks, the
presence of four digits and the mesaxonic condition can be clearly ob-
served. In the fifth footprint of LPP-IC-0001 (holotype) (Fig. 11A) and
sixth footprint of LPP-IC-0003 (Fig. 11B) although the presence of digits
is less clear, the tetradactyly can also be attested. Note the greater length
of digits III and IV, and the possible presence of claws in LPP-IC-0004 and
LPP-IC-0011.
The trackways which clearly have handprints are LPP-IC-0001 (holo-
type), LPP-IC-0003, LPP-IC-0004 and LPP-IC-0005. In this case, it was eas-
ily possible to calculate the distance between the hands and feet sets,
which was 4,36 ± 0,77, 5,3 ± 0,61, 3,76 ± 0,14 and 4,42, respectively.
However, in LPP-IC-0009 (Fig. 12A–B), LPP-IC-0013 (Fig. 12C) and LPP-
IC-0014 (Fig. 12D) very subtle circular structures can be observed. They
Fig. 10. Paratypes of Brasilichnium saltatorium isp. nov. A. LPP-IC-0012; B. LPP-IC-0008; C
resemble handprints with small dimensions. The distance between such
structures and the feet can be considered null since overlap occurs.
These curious structures are also present on a slab in Leonardi and
Oliveira (1990) and Leonardi et al. (2007) without number deposited in
the Departamento Nacional de Produção Mineral (DNPM) of Rio de
Janeiro, where the same hopping behavior can be observed (in a upslope
effort). However, in this specimen, these structures can be more easily
seen, and are positioned just behind the sets of feet impressions.
Fig. 11. Details of the digits on Brasilichnium saltatorium isp. nov. pes. A. Fifth footprint of LPP
footprint of LPP-IC-0011; E. First footprint of LPP-IC-0011. Note the presence of four digits in
Scales in centimeters.
Discussion
In paleoichnological scientific literature, the description of several
ichnotaxa based on preservational variations is very common. As an ex-
ample, we can mention the work of McKeever and Haubold (1996), in
which reclassification of several Permian tetrapod tracks was held.
These tracks were previously assigned to different ichnogenus and spe-
cies, solely because of their morphology varied due to preservational
features. The work of Lockley (2011) can also be mentioned. Several
ichnogenera from Navajo Formation (Lower Jurassic) were created
based on the presence/absence of autopodia on the trackways. Lockley
(2011) considered them all variations of B. elusivum, and explained
they where variants caused by means of preservation.
In the present study the locomotory pattern which differentiates B.
elusivum and Brasilichnium saltatorium isp. nov. reflects, not a
preservational artifact, but a distinct behavior. Sarjeant and Carpenter
(1990) proposed distinct ichnotaxonomical classifications based on dif-
ferent behaviors of the same trackmaker when morphological differ-
ences can be observed in the trace fossils, and we adopt this proposal
here in this work. We mean there is a real biological variation behind
the morphological differences. The change in locomotory behavior sig-
nificantly alters the morphology of autopodia on tracks and trackways
P-IC-0007. Scales in centimeters. Directionof movement towards the top of the picture.
configuration (Fig. 13).
A good example which reinforces this argument are LPP-IC-0006
(Fig. 9F), LPP-IC-0007 (Fig. 10C) and LPP-IC-0012 (Fig. 10A)
Brasilichnium saltatorium isp. nov. trackways. In LPP-IC-0006 and LPP-
IC-0012, at theproximal part of the trackways, the producer's locomoto-
ry behavior is notably cursorial, then, the organism switched its gait to a
hopping action. The distance of oblique pace in LPP-IC-0006 decreases
considerably before the first jump, indicating an adjustment for
-IC-0001; B. Sixth footprint of LPP-IC-0003; C. Fourth footprint of LPP-IC-0004. D. Third
all images. Also note the digits III and IV are considerably larger in relation to II and V.
31P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
saltatorial locomotion. The small distance traveled by the hopwas relat-
ed to the beginning of the movement, where the animal begins to get
impulse and velocity. On both slabs, there are other trackways indicat-
ing typical cursorial locomotion. Comparing its pes morphological fea-
tures (e.g. width, length, and L/W ratio) with feet impressions of
Brasilichnium saltatorium isp. nov., no significant differences were ob-
served (P N 0.05). In LPP-IC-0007, in beginning of trackway, the
producer's locomotory behavior is saltatorial, then, the organism
switched its gait to cursorial. We note the higher VPD value (3,69 ±
0,66) when the cursorial locomotion was adopted. This may indicate a
decrease in the animal's speed at the beginning of curosrial locomotion,
thus increasing the vertical distance between the feet, in relation to the
midline.
With several trackways presenting the two locomotorial styles, this
may indicate that the same organism could have produced bothmodes.
Since the environmental and preservational conditions were the same,
the behavior and locomotory dynamics are responsible for the observed
variation (see Falkingham, 2014).
When the L/W ratio of LPP-IC-0003, LPP-IC-0006, LPP-IC-0007, LPP-
IC-0012 and LPP-IC-0014 is compared with the measurements of B.
elusivum holotype (MNRJ 3902-V) and 1st paratype (MNRJ 3903-V),
no significant difference (P N 0.05) is observed. The LPP-IC-0004, LPP-
IC-0006, LPP-IC-0007 and LPP-IC-0012 trackways presenting saltatorial
locomotion are differents from holotype LPP-IC-0001. When
Brasilichnium saltatorium isp. nov. holotype (LPP-IC-0001) pes L/W
ratio is compared with B. elusivum holotype (MNRV 3902-V) and 1st
paratype (MNRV 3903-V), a significant statistical difference
(P b 0.001) is observed between the two different modes of locomotion.
However, no difference is found (P N 0.05) between the two tracks indi-
cating cursorial gaits. This difference may be due to extramorphological
Fig. 12. Subtle elliptical structures located just behind the feet marks, possibly associated with h
0009; C. Two sets of LPP-IC-0013;D. Second set of pes of LPP-IC-0014. Note the lower quality of p
short distances between these structures and the feet impressions. Scales in centimeters. Direc
features controlled by preservational aspects, as suggested in the
neoichnological experiments previously presented. Nevertheless, the
oval heel pad of the pes, as well the same trackways with different
locomotorial behavior, still reinforce the position of this new
ichnotaxon within ichnogenus Brasilichnium.
Another feature that may be compared between the two icnotaxa is
the degree of heteropody, described as being high for B. elusivum. MNRJ
3902-V (B. elusivum holotype) has manus length and width of 0.88 ±
0.25 cm and 0.98 ± 0.3 cm, respectively, while LPP-IC-0001
(Brasilichnium saltatorium isp. nov. holotype) has manus length and
width of 2.2±0.17 cmand 1.68±0.2 cm, respectively. This notable dif-
ference could be explained by the animal's distinct movements. When
descending the paleodune, the organism employing a hopping move-
ment would have produced larger hand impressions, as these penetrat-
ed the substrate to serve as a support for the body. The higher energy
present in this type of movement also creates larger drag, resulting in
extramorphological variation which tends to increase the size of
autopodia prints.
LPP-IC-0009, LPP-IC-0013 and LPP-IC-0014 slabs, described herein,
and the specimen without number from DNPM, reported by Leonardi
and Oliveira (1990) (Plate XII - E) and Leonardi et al. (2007) (Fig. 3F),
have hopping trackways in upslope directions. In both, the round struc-
tures associated with hand impressions near the posterior margins of
the footprints (Fig. 12) show a high degree of heteropody, similar to
what is observed in B. elusivum.
Of the twelve slabs herein described attributed to Brasilichnium
saltatorium isp. nov., those with observable digits shows a mesoaxonic
and tetradactyl conditions. The digit configuration of Brasilichnium
saltatorium isp. nov. is very similar to that observed in B. elusivum,
where the digits that have visible marks are II, III, IV and V (see
and impressions (see indicative arrows). A. First set of LPP-IC-0009; B. Fifth set of LPP-IC-
reservation of the elliptical structures associated to handprints A, B andD. Also, observe the
tion of movement towards the top of the picture.
32 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
Fernandes and Carvalho, 2008). The number of fingers is the same. The
mesoaxonic condition, however, deviates from the pattern observed in
B. elusivum, which is usually ectaxonic. More closed digits could be asso-
ciated with increased support for hopping locomotion.
LPP-IC-0001 and LPP-IC-0011 digits morphology and foot size are
similar to Chelichnus bucklandi Jardine, 1850, an ichnotaxon described
for Permian aeolian deposits. Many millions of years separate these
trace fossil producers, but these features may represent an adaptive
convergence to life in sandy deserts.
Besides Brasilichnium saltatorium isp. nov., the ichnospecies
Ameghinichnus patagonicus Casamiquela, 1961, also ofmammaliform af-
finity, likewise present saltatorial behavior, also reviewed by Rainforth
and Lockley (1996). Valais (2009) attests the occurrence of symmetrical
and asymmetrical locomotion related to this ichnotaxon in La Matilde
Formation, Argentina (Middle Jurassic). In addition to the differences
in age and paleoenvironmental context of this ichnotaxon and
Brasilichnium saltatorium isp. nov., the pes and manus morphology of
both ichnotaxa differs sufficiently to infer different producers, yet with
the same locomotory skill. Manus and pes of Ameghinichnus patagonicus
are clearly pentadactyl with sprawled digits. Its heteropody is very low
and the hop distance has on average 9.16 cm (n=8). Because of the op-
timal preservation (Valais, 2009, Fig. 3B), the dimensions of the hands
and feet of Ameghinichnus patagonicus represent the actual degree of
Fig. 13. Representative scheme of two distinct modes of locomotion depending on the
organism behavior. A. Brasilichnium elusivum holotype (MNRJ 3902-V). B. Brasilichnium
saltatorium isp. nov. holotype (LPP-IC-0001). Note the difference in the autopodia
configuration between the trackways. Scale: 5 cm. Direction of movement towards the
top of the picture.
the organism heteropody, where extramorphological features have lit-
tle influence, unlike LPP-IC-0001 (holotype).
Leonardi (1994) described a hopping trackwayof tridactyl footprints
from Botucatu Formation (ASRB 95) and attributed it to dinosaurs.
Later, however, Rainforth and Lockley (1996) noted the transverse
heel and sub equal digits dimensions and assigned it to a mammaliform
producer. This track (ASRB 95) is similar in pes size, digits morphology
and hop distance to LPP-IC-0011 trackway. The tridactyl conditionmost
likely is explained by its preservation as undertrack.
Also in the Mesozoic, Lockley and Foster (2003) described a new
ichnogenus,Schadipes, from the Laramie Formation (Upper Creta-
ceous) in Colorado. Schadipes producer could change its movement
pattern between hopping and cursorial gaits. This would be the first
ichnotaxon strictly associated with amammalian producer from the
Cretaceous period. The possible candidates for Schadipes producers
are multituberculates and marsupials, based on the patterns of
movement and autopodia morphology, which significantly differ
from Brasilichnium.
In the Cenozoic, saltatorial ichnogenus are described from Flagstaff
and Brown Park formations (Lockley and Milner, 2014). Ichnotaxon
Ranipes laci, from Flagstaff Formation, was likely produced by an am-
phibian. Its average hop distance is 5.7 cm (n = 2) and the pes does
not register anterior to the manus in the locomotion cycle. Musaltipes,
from the Brown Park Formation, is associated with rodents displaying
bipedal and quadrupedal behaviors. Its autopodia configuration resem-
bles that of Brasilichnium saltatorium isp. nov., however, it has five digits
and tail drag at themiddle portion of the track,which until nowwas not
observed for Brasilichnium.
The ichnotaxa mentioned above have different producers, but they
all display similar locomotory patterns. This represents a convergence
in behavior. The hopping gait in Brasilichnium producers could have
been used to escape predators or chase prey, by increasing its displace-
ment speed (Gasc, 2001). Another possibility is the development of a
specialized locomotion in response to the life in sandy deserts on
which the animal must constantly move on inclined planes (Rainforth
and Lockley, 1996). Also, the saltatorial gait may have served to avoid
prolonged contact with hot sand, as demonstrated by Nachtigall
(1996) for beetles. However, it should be remembered that the,
Brasilichnium saltatorium isp. nov. producer did not strictly move
around using hops, as is the case of themodern kangaroo. Brasilichnium
producer displayed at least two distinctmodes of locomotion. Amodern
example of an animal which uses this strategy is the northern brown
bandicoot, a marsupial (Peramelidae) from Australia. Its casual way of
locomotion is a quadrupedal cursorial gait, but as it increases its
speed, its displacement becomes saltatorial (Bennett and Garden,
2004).
Unfortunately, to date, body fossils of the possible Botucatu Forma-
tion trackmakers were not found. Thus, potential producers can only
be inferred based on track configurations, autopodia morphology,
mode of locomotion, as well as bibliographical analysis of fossil groups
present in cronostratigrafically related units.
Despite the absence of such fossil, inferences can bemade about the
skeletal morphology of Brasilichnium producers (see the work of Chen
and Wilson, 2015). Modern taxa with hopping locomotion usually
have elongated hindlimbs and the forelimbs are generally used for ac-
tivities such as food handling or digging. In hopping animals, the ischi-
um is also usually elongated, optimizing saltatorial ability. Chen and
Wilson (2015) posit that the saltatorial movement arose in the Late Cre-
taceous, disagreeing with the ichnofossil record, which includes both
Ameghnichnus (Middle Jurassic) and Brasilichnium saltatorium isp. nov.
The authors may have considered only taxa discovered in Central Asia.
Several authors associate Brasilichnium tracks with a derived group of
cynodonts, the Tritylondontidae, organisms defined as herbivores.
Winkler et al. (1991) documents body fossils from Tritylondontidae in
the Navajo sandstone (Lower Jurassic), togheter with footprints assigned
to Brasilichnium. Martinez et al. (1996) describe a small carnivorous
33P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
animal with high affinity to Tritylodontidae, Ecteninion lunensis, in the
Ischigualasto Formation, Upper Triassic of Argentina. This attests the pres-
ence of these animals in South America. The Botucatu Formationwas pre-
viously estimated be the Triassic in age, but is now safely located at the
beginning of the Cretaceous. It is known Tritylondontidae persisted to
the Early Cretaceous, having representatives in Russia (Leshchinsky et
al., 2003) and Japan (Matsuoka et al., 2016). We can not discard the hy-
pothesis Brasilichnium could have been produced by these animals.
The teromorphoid affinity (Pelycosauria) can be more safely chal-
lenged since the groupwas extinct in the Triassic. Despite teromorphs in-
dicating mammaliform characteristics, Brasilichinium locomotion was
relatively derived, more similar to Mammaliformes (i.e. narrow tracks,
high pace angulation, hopping gait, rounded fingers, erect posture, etc.).
In a review on basal mammals found in South America during the
Mesozoic, Rougier et al. (2010) discuss the presence of two species of
Australosphenida and one of the Triconodontidae in theMiddle Jurassic,
as well as a basal Theria in the Early Cretaceous, all from Argentina.
These occurrences attest the presence of basalmammals in SouthAmer-
ica before andduring deposition of the Botucatu desert, and reveal other
potential groups for Brasilichinium producers.
Valais (2009) lists features that should be taken into account in de-
terminingwhether the producer of the track hasmammaliform affinity.
Among them are: 1) the presence of five digits on manus and pes; 2)
digits impressions of similar shape and size; 3) mesaxonic footprints;
4) not sprawling posture and specialized locomotion mode; and finally,
5) relatively small footprints. Of these characteristics, the presence of
five digits is the only one which does not agree with the footprints at-
tributed to Brasilichnium. Digit I, even if present, did not contact the sub-
strate (Fernandes and Carvalho, 2008).
4. Discussion
4.1. Preservational and locomotorial aspects
In aeolian environments such dune deposits, epistratal bioturbations
usually are preserved in the lee side of the dune, sheltered from the
wind (foreset). The sediment is removed from the exposed windward
face and deposited on the opposite, lee side. The Botucatu Formation
ichnites were produced on inclined planes, and sand crescent structures
behind upslope tracks occur as the result of sediment displacement in re-
sponse to locomotion effort (Leonardi et al., 2007).When progression oc-
curs towards the top of the dune, the crescents are behind the posterior
part of the tracks, and when the animal goes down the inclined plane,
these structures are observed in front of the footprint. It may also be
noted that such structures may be located along the side of the footprint
when the animal moves along the contours of the inclined plane.
According to Leonardi et al. (2007), 90–95% of Botucatu Formation
tetrapod footprints are of low quality, represented only by a rounded
or elliptical depression on the substrate, without morphological details.
However, several tracks from Araraquara show high-level detail preser-
vation, including the conservation of digits morphology. An example is
LPP-IC-0004 (Fig. 11C), which preserves digits morphology in the feet
impressions. Likewise, LPP-IC-0011 slab (Fig. 11D–E). Besides defined
as a undertrack, it also preserves digits morphology in high detail. Final-
ly, the specimen used by Fernandes and Carvalho (2008) on the diag-
nostic review of Brasilichnium elusivum. It shows an impressive degree
of detail preservation not only preserving the digits morphology, but
also the pes and manus pads.
When the footprints are produced andpreserved in dry sand, it is ex-
pected that there will be a lack of diagnostic features. In this condition,
only the autopodia outline is preserved. The sediment is lack of cohesion
does not allow the animal's detailed footmorphology to register (Brand,
1996). Furthermore, extramorphology plays a great role, as demonstrat-
ed by Brand (1979). Footprints produced in the dry sand have high L/W
ratio whencompared with tracks produced in sands with higher hu-
midity levels.
Thus, for the production of high quality footprints, including the
presence of small digit traces - as the ones preserved in Brasilichnium
-, the sediment grains necessarily need a certain level of cohesion. The
cohesion is given by moisture. Low levels of moisture makes the sub-
strate more cohesive, but plastic enough to preserve the morphology
of organism's autopodia (McKeever, 1991). Brand (1996) demonstrates
this hypothesis producingwell preserved trackways inmoist sandy sub-
strates, and extends his conclusins to tracks produced in aeolian
environments.
In the Botucatu desert, as well as in other deserts - both past and
present -, the moisture responsible for high-quality footprint preser-
vation can be derived from two sources: 1) the night dew; 2) and the
presence of groundwater in the dunes, as postulated by Leonardi
(1980). Żmudzka et al. (2014) analyzed the influence of night dew
in the sand cohesion in a dune field in Western Sahara. This author
came to the conclusion the water vapor condensation can occur
more than one hundred days a year. The supply of water from this
source could be equal to or greater than the provided by rainfall it-
self, thereby helping to maintain the cohesion of the substrate. How-
ever, this moisture does not affect the deeper layers of sand. The rain
is responsible for the water presence in higher (i.e. decimetric)
depths, which there persists for several days. The presence of sedi-
mentary structures indicating pluvial events occurred in the
Botucatu Formation supports the hypothesis of groundwater also
influencing the preservation of footprints. The groundwater would
recharge after each rainfall episode and the phreatic level would
then be higher on the dune, providing moisture in the subsurface,
and increasing the potential for vertebrate trace fossils preservation.
Many footprints could be formed in the subsurface, favoring the preser-
vation of somemorphological features.When a footprint is produced in
the subsurface, the moisture of the substrate can act favoring the mold.
Also, the autopodia impression is immediatly isolated from the surface.
This increases the preservation potential by decreasing the action of de-
structive environmental agents and/or trampling.
Aeolian environments are common places for undertracks forma-
tion. Undertracks are produced due to the animal weight being trans-
mitted to the lower layers of sediment. Milàn and Bromley (2006)
(Table 1) andMilàn and Bromley (2008) (Fig. 5) did experiments to in-
dicate that as feet penetrate into the layers, the footprint decreases in
size and loses relief. LPP-IC-0012 Brasilichnium saltatorium isp. nov.
trackway (Fig. 10A), for example, could then be considered an
undertrack because of the absence of clear contours defining its limits.
Another issue of great importance for the understanding of the
Botucatu Formation paleoichnofauna, is the presence of morphotypes
with and without heteropody within Brasilichnium. B. elusivum tracks
are assigned to quadrupedal animals, even when themanus are not ob-
served in the fossil trackway. Lockley (2011) attributed Bipedopus and
Semipedopus to preservational variations of B. elusivum. On these
ichnotaxa, hand impressions are not preserved or can not be clearly
seen. Fernandes and Carvalho (2008) infered that B. elusivum
heteropody occurs only when the animal has pace anglulation between
105° and 120°.
A possible explanation for homopody in Brasilichniumwould be the
overlap of the tiny hands by the larger feet when the animal takes a
higher speed and consequently the stride length increases. When com-
paring B. elusivum holotype (MNRJ-3902-V) (Fig. 7A) and its 1st
paratype (MNRJ-3903-V) (Fig. 7B), oblique pace and stide length
show a significant statistical difference (P b 0.015). The average oblique
pace is 5.94 ± 0.79 cm for the holotype and 6.88 ± 0.21 cm for the
paratype. The average stride length is 9.54 ± 2.24 cm for the holotype
and 11.83±0.42 cm for the paratype. Neverthless, when the pace angu-
lation is compared between the same samples, no difference (P N 0.05)
is obtained, and the average is 107.35 ± 24.09 cm for the holotype and
118 ± 2.62 cm for the paratype.
In Brasilichnium saltatorium isp, nov., heteropody seems to be related
to the direction of the animal'smovement relative to the inclined plane.
Another interpretation is that the footprints producedwhen ascend-
ing the paleodune are undertracks. The hands would almost not leave
34 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
marks because they represent a subsidiary support. If in fact LPP-IC-
0009, LPP-IC-0013 and LPP-IC-0014 tiny oval structures correspond to
hand impressions, the manus L/W ratio for the ascending movement
are smaller due to extramorpological features. Contrary to what is ob-
served in descending movement, where the manus length is greater
than its width. Thus, the degree of heteropody is larger and becomes
more evident when the animal climbs the inclined plane. The
neoichnological experiments here presented can sustain such argu-
ments, as well as the position of the manus observed in the upward
and downward movements. The distance between the pes and manus
sets in the neoichnological experiment is practically zero on the upward
displacement. This is also observed in the fossil tracks, reinforcing the
idea those tiny oval structures correspond to hands impressions. The
distance of pes and manus sets is smaller in the upward movement
due to the increased locomotor effort. The manus surpassing by the
pes is difficulted by the dynamics of movement on the inclined plane.
This is confirmed by the PMD parameter in the neoichnological experi-
ment, which was statistically different between the ascending and de-
scending treatments (P N 0.05).
As for the hop distance, there were no statistically significant differ-
ences in the neoicnological experiments between the ascending and de-
scending treatments (P N 0.05). Which led us to conclude, this
parameter is most probably controlled by the organism's behavior at
the timeof locomotion. In the fossil specimens, therewas a clear distinc-
tion between the hop distances in descending and ascending trackways.
The hop distances were significantly higher when the animal was de-
scending the paleodune. This may be explained mainly for the greater
ease of movement. Yet higher locomotion speeds could have been
intentionaly developed by the organism in those particular situations
or, also, skeletal conditions, such as more enlongated hind limbs,
could have caused this particular track configuration.
4.2. Comments on Botucatu Formation paleoecology
Botucatu Formation paleoecology can be interpreted through its
trace fossils and non-biogenic sedimentary structures. The trace fossils
from Araraquara and São Carlos region are particularly relevant for the
undestanding of Botucatu desert paleoenvironment and paleobiota. In
the Araraquara region, due to geological and paleontological evidence
of higher humidity, vegetation adapted to grow in sand dunes could
have occured in the interdune valleys, even though no fossil plant has
yet been discovered in the area. This vegetation in turn, could have sup-
ported the scarce herbivorous fauna recorded in São Bento quarry sand-
stones by footprints of ornithopod dinosaurs (Hack, 1941; Fernandes et
al., 2004; Fernandes and Carvalho, 2007).
The vegetation could have meet its need for water from the subsur-
face humidity from groundwater (Ho et al., 2004). In rainy periods
In trackwayswhere themotion is downward (i.e. holotype LPP-IC-0001,
LPP-IC-0003, LPP-IC-0004 and LPP-IC-0005), the hands impressions are
clearly visible (it should be noted that in LPP-IC-0004 trackway, hand
impressions are collapsed, but the sets are present). When the motion
is upwardsin relation to the inclined plane, tiny circular structures
which may be related to hand impressions occur in LPP-IC-0009, LPP-
IC-0013 and LPP-IC-0014 (Fig. 12). The difference in hand impressions
size, therefore, are notable.
Just as in the tracks produced byMeriones unguiculatus, the manus
and pes can overlap when the animal is moving up on the inclined
plane. This can lead to the interpretation of a bipedal homopodic condi-
tion. The bipedal condition, however, should not be totally dismissed
because the animal could maintain the support on the hind limbs
when climbing the dune, and use the anterior limbs as subsidiary sup-
port, when going down on the inclined plane.
where water availability is not a limiting factor, a significant plant
biomass could have been formed, positively affecting the entire fauna
of the region providing food and shelter (Hadley and Szarek, 1981).
In the northeastern portion of Botucatu Formation (Minas Gerais
State), Pires et al. (2011) documented the presence of indigenous coni-
fer fossil trunks. The development of this arboreal paleoflora must have
demanded water, suggesting this whole area was positioned in a mar-
ginal portion of the Botucatu desert. Pires et al. (2011) suggested this re-
gion was highly influenced bymonsoonwinds which broughtmoisture
inland from the Tethys Sea.
The unavailability of water and nutrients and a possible increase in
the transport and deposition of sand in certain areas of the Botucatu de-
sert could have led to the limitation and/or elimination of the local veg-
etation, affecting the establishment of an associated fauna (Hack, 1941;
James et al., 2005). This may be the case of some Botucatu Formation
sites inwhich the ichnofauna register is scarce or non-existent, suggest-
ing it has been deposited in a greater aridity (e.g. Nowatzki and Kern,
2000; Scherer and Lavina, 2006). In these areas, the loss of water
through evapotranspiration should have been greater than the gain by
precipitation, therefore, the development of a resident fauna and flora
was not possible.
Little can be inferred about the amount and intensity of precipitation
during the deposition of Botucatu Formation. In current deserts, it is es-
timated that an annual rainfall of 25–75mm is sufficient to sustain veg-
etation (Noy-Meir, 1973). Webb et al. (1978) attest at least 38 mm of
annual rainfall can maintain evergreen vegetation. It is confirmed that
paleorain events occurred in the São Bento quarry area during the
Botucatu Formation deposition. However, its occurrence was
apperently rare, since rain impact craters and other sedimentary struc-
tures associated with pluvial events are very few, both in scientific col-
lections, and on slabs used for paving public pavements (Fernandes and
Corrêa, 2007). This represents many decades of sandstone excavation
from several stratigraphic levels.
Water availability is an important environmental factor in arid eco-
systems since it limits the productivity. The productivity is closely
linked to frequency, intensity and duration of precipitation (Hadley
and Szarek, 1981; Ludwig, 1987). Unfortunately, due to the purely com-
mercial exploitation of Botucatu sandstone, often without the presence
of researchers, it is not possible to determine the stratigraphic context of
many slabs with trace fossils and important non-biogenic sedimentary
structures. So the frequency, extension, duration and intensity of
paleorains and paleorain intervals is unknow.
The essential nutrients for plant growth also play a central role
throughout the desert community structure. Seely and Louw (1980)
show a deficiency of nutrients in the current Namíbia desert resulted
from the low decay rate and the explosive flora growth after rainfall
events. This vegetation blooming depleted the nutrients faster than
they could be replenished.
Considering all the limiting factors (e.g. productivity, availability of
water and nutrients, etc.), the Botucatu desert fauna and flora may
have been restricted to the most favorable areas, forming productive
local communities with high biological activity, like Oasis, typical isolat-
ed desert environments. These places may have served as sanctuaries
where wildlife could find food and shelter: islands of biodiversity. The
precipitation carbonates is very commom in deposition environments
such as ephemeral lagoons and interdune ponds (e.g. Parrish and
Falcon-Lang, 2007; Smith and Mason, 1998). Carbonate lenses were
not reported in the Araraquara and São Carlos region. Therefore, the
Oasis hypothesis is only sustained by the abundance of trace fossils, in-
dicating a possible route for water (e.g. Paik et al., 2001), and the sedi-
mentary structures indicating the paleorainfall events. Loope and
Rowe (2003) infer wet interdune environments for Navajo desert
(Lower Jurassic, 190Ma,West U.S.A.), evenwithout evidence of carbon-
ate lenses. The hypothesis is, likewise, solely supported by the abundant
ichnofauna. The authors' explanation for this is based on the high degree
of water dilution, that may have prevented the carbonate precipitation.
In rainy periods, groundwater is supplied and migrate towards the
surface. Water with few solutes is then discharged in the interdune
areas, providing favorable environments for the establishment of plants
and animals.
Seely (1991), studying the Namibian desert ecology, proposes com-
munity structure is mainly controlled by abiotic factors, rather than bi-
ological interactions. Thus, the so called autoecological hypothesis could
explain the community structure since populations usually have low
densities, making rare interactions. In a recent study, Francischini et al.
(2015) compare the Guará Formation (fluvio-aeolian, Upper Jurassic)
and Botucatu Formation (aeolian, Lower Cretaceous) dinosaur
ichnocenoses. They found differences in faunal composition and dino-
saurs sizes. In Guará Formation, the estimated size of different dinosaur
groups were higher when compared to the same groups of dinosaurs
found in the Botucatu Formation (except Sauropoda, exclusive of the
first unit). The greater aridity during the deposition of the Botucatu For-
mation in relation to the Guará Formation may have influenced on the
size of the dinosaurs, due to stressful conditions. The absence of trace
fossils of Sauropoda in Botucatu Formation may be evidence of the
autoecological hypothesis structuring the Botucatu paleodesert com-
munity, since large animals possibly had difficulties in prospering in
arid environments (Louw and Seely, 1982).
In an oasis, where both productivity and population densities are
higher and the intensity of stressful conditions decrease, the biological
interactions can play an important role in structuring the community.
The Botucatu Formation paleocommunity could have been structured
adult beetles, therefore linking substrate and surface sub-web trophic
components (Polis, 1991).
Due to the uncertainty and fluctuations in the availability of re-
sources in desert ecosystems, feeding behavior tends to be opportunis-
tic and flexible. Generally, most consumers are omnivorous, forming
highly connected food webs (Polis, 1991). In this context, Brasilichnium
producer probably played the role of secondary consumer, being an om-
nivore and feeding on various levels of the trophic web, for example, on
insects, arachnids, and different plantmaterial. It preferably changed its
diet according to the availability of resources (similar to what is de-
scribed by Hadley and Szarek, 1981).
Fluctuations in environmental conditions, such as daily tempera-
ture amplitude, can also influence the fauna behavior. Lucas et al.
(2006), Riese et al. (2011), and Rowland and Mercadante (2014) de-
scribe the presence of burrowing structures in the Navajo and Aztec
sandstones, both from the Lower Jurassic, Western United States.
Based on the size and configuration of these structures,the above-
cited authors suggest Brasilichnium producer was most likely the or-
ganism responsible for those structures. In Brazil, Dentzien-Dias et
al. (2008) recorded the presence of possible burrows of 20 cm
width in a Guará Formation paleodune where theropod footprints
were also found.
So far, structures associated with burrows were not found in the
Botucatu Formation. However, based on the above-cited literature,
Brasilichnium producers could have presented fossorial behavior as a re-
tu Fo
35P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
according a mosaic of environments, some drier with low productivity
as the dunes, other wetter with higher productivity as the rare oasis.
Based on the ichnological records, inferences about the Botucatu de-
sert trophic web can bemade (Fig. 14). An important component of the
trophic web in arid environments is the scavengers because the micro-
bial decomposition is limited due to low humidity. Biomass produced
detritivorous organisms by its turn, can be exploited by carnivores con-
sumers (Hadley and Szarek, 1981).
The endostratal and epistratal trace fossils found in the Botucatu For-
mation can be assigned to macro detritivorous organisms. In the first
case, beetle larvae had their tracks preserved while feeding on waste.
In the second case, the activity of beetles on the surface was preserved.
Climbing up a level in the food web, the record of scorpions and spiders
activity, both epiestratal organisms, have been mentioned in literature
(Fernandes et al., 2014.). These animals could feed on the larvae and
Fig. 14. Possible trophic interations between groups registered by their traces for Botuca
Scorpion, by Gareth Monger. 5. Mammaliform, by Michael B. H. 6. Theropod, by C. Abraczinska
sponse to avoid adverse conditions of the environment. Only a few cen-
timeters into the sand, the conditions related to temperature and
humidity were less extreme (Edney et al., 1974; Seely et al., 1988).
Burrowing behavior in response to daily fluctuations in environmental
conditions could create microclimates, allowing the organisms face to
adversities. Currently, there are small desert mammals which exhibit
such fossorial behavior. They look for shelter under the substrate in
stressful situations (Degen, 1997).
Regardingmodernmammals foraging, non-biotic (e.g. high temper-
ature during the day) and biotic (e.g. predation) factors could influence
the behavior of these animals. Nocturnal activity and fossorial behavior
are strategies adopted to escape both the adverse conditions, as well as
predation (Reichman and Price, 1993). Predators in the Botucatu desert
were represented by theropod dinosaur's fossil footprints of at least two
distinct morphotypes, Coelulosauria and Carnosauria (Fernandes et al.,
rmation. 1. Coleoptera, by Melissa Broussard. 2. Ornithopod, by Steveoc 86. 3. Spider. 4.
s. All credited images are under licence: https://creativecommons.org/licenses/by-sa/3.0/.
36 P.V. Buck et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 466 (2017) 21–37
2011). The food resource of these organisms could mainly be
Brasilichnium producers and ornithopod dinosaurs.
Yet, Botucatu desert paleocommunity can be correlated with
current deserts of the world and also compared with other past
paleoenvironments (e.g. Lockley and Hunt, 1995). As new researches
are conducted, new morphotypes and ichnotaxa can be added, im-
proving and refining the paleoenvironment interpretation and the
paleoecological relationships.
5. Conclusions
The new icnotaxon here described shows a real biological variation
due to differences in locomotory behavior. Brasilichnium saltatorium
isp. nov. presents a hopping asymmetrical gait, which reflects in a clear-
ly different limb configuration in relation to the typical cursorial loco-
motion described for B. elusivum. This justifies the new nomenclature
here proposed, following Sarjeant and Carpenter (1990).
B. elusivum and Brasilichnium saltatorium isp. nov. may have been
produced by the same mammaliform organism, since fossil evidence
show switching between the cursorial and saltatorial (hopping) loco-
motion. Statistical analysis considering autopodiamorphology also sug-
gests this relation. The hopping behavior was probably used to ensure
greater speed when escaping from predators or hunting arthropods,
or even to traverse the slopes and hot sand faster.
The heteropody and homopody may be related to the direction of
movement. The descending tracks always show hands impressions. In
the ascending trackways, the manus can be overlapped by the pes due
to the shorter distance between autopodial sets. When the organism
climbs the inclined plane, the hands can also leave no marks. This is
given by the front limbs subsidiary role in the movement or undertrack
preservation. Extramorphological features were observed and interfere
with the actual dimensions of autopodia.
The presence of somepeculiar sedimentary structures and the abun-
dance of trace fossils indicate a relatively high humidity during the de-
position of Botucatu sandstone in the Araraquara region. Possible
ephemeral ponds may have formed locally, allowingwildlife to flourish
in seek of food and shelter. Based on comparisons with current desert
organisms and burrows described for other aeolian units, ichnogenus
Brasilichnium producers were likely small omnivores with fossorial
habits.
Acknowledgements
Wewould like to thank the financial support provided by CNPq (Na-
tional Council for Scientific and Technological Development, process no.
149694/2014-8) and the Graduate Program in Ecology and Natural Re-
sources of UFSCar (PPGERN-UFSCar). We would like to thank the sug-
gestions of M. G. Lockley, whose comments helped to improve the
manuscript significantly. We are also grateful to the Itaporanga Mining
for supplying sand for the neoichnological experiments and the
Laboratório de Paleoecologia e Paleicnologia team for all the support
provided throughout this work. Finally, Deise Henrique and Lilian
Alves da Cruz are thanked for the great reception in theMuseu Nacional
(Rio de Janeiro State) scientific collection and for helping in handling
the slabs containing the holotype and 1st paratype of Brasilichnium
elusivum.
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