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Irajatherium hernandezi is a poorly known non-mammaliaform cynodont from the Late Triassic of southern Brazil. A new specimen of this cynodont was found in recent fieldwork to the type-locality, Sesmaria do Pinhal (Candelária), providing new insights into the anatomy of this mammalian forerunner. This specimen comprises a partial skull preserving the left canine, two left and three right postcanines, and an isolated exoccipital; the left dentary with the canine and postcanines; a fragment of the right dentary; the proximal portion of the left partial humerus; the right scapula; and indeterminate fragments. Based on new material, it is here suggested that I. hernandezi presents: a rostrum broad and short, possibly long as the temporal region; three foramina on the lateral surface of the maxilla, that could correspond to the external openings of the rostral alveolar, infraorbital, and zygomaticofacial canals; a slender zygomatic arch and an absent postorbital bar; a posteriorly wide temporal fossa; a long secondary palate, slightly surpassing the level of the last postcanine tooth; the cerebral hemispheres of the cranial endocast divided by a median sulcus; the scapular blade long and straight, and the postscapular fossa absent in lateral aspect. Finally, I. hernandezi and other tritheledontids were included in a phylogenetic analysis of Eucynodontia. The analysis recovered unresolved relationships for ictidosaurs/tritheledontids, nested within a polytomy with Tritylodontidae and a clade composed by Pseudotherium argentinus, Botucaraitherium belarminoi, Brasilodon quadrangularis, and Mammaliaformes.

Recent studies have analyzed and described the endocranial cavities of caviomorph rodents. However, no study has documented the changes in the morphology and relative size of such cavities during ontogeny. Expecting to contribute to the discussion of the endocranial spaces of extinct caviomorphs, we aimed to characterize the cranial endocast morphology and paranasal sinuses of the largest living rodent, Hydrochoerus hydrochaeris, by focusing on its ontogenetic growth patterns. We analyzed 12 specimens of different ontogenetic stages and provided a comparison with other cavioids. Our study demonstrates that the adult cranial endocast of H. hydrochaeris is characterized by olfactory bulbs with an irregular shape, showing an elongated olfactory tract without a clear circular fissure, a marked temporal region that makes the endocast with rhombus outline, and gyrencephaly. Some of these traits change as the brain grows. The cranial pneumatization is present in the frontal and lacrimal bones. We identified two recesses (frontal and lacrimal) and one sinus (frontal). These pneumatic cavities increase their volume as the cranium grows, covering the cranial region of the cranial endocast. The encephalization quotient was calculated for each specimen, demonstrating that it decreases as the individual grows, being much higher in younger specimens than in adults. Our results show that the ontogenetic stage can be a confounding factor when it comes to the general patterns of encephalization of extinct rodents, reinforcing the need for paleobiologists to take the age of the specimens into account in future studies on this subject to avoid age-related biases.

In this paper, we study the postcranial morphology (humerus, ulna, innominate, femur, tibia, astragalus, navicular, and metatarsal III) of Neoepiblema, a giant Late Miocene South American rodent, searching for evidence about its paleobiology based on unpublished specimens from Solimoes Formation (Upper Miocene, Brazil). The study includes a morphofunctional analysis of the postcranial bones and a comparison with extant and extinct rodents, especially Phoberomys. The morphofunctional analysis of the postcranial bones suggests that Neoepiblema (as well as Phoberomys) would have a crouched forelimb that was not fully extended, with powerful pectoral and triceps musculature, and able to produce movements of pronation/supination and possibly with a hand able to grasp. The combination of characters of the innominate bone, femur, and tibia indicates a predominance of parasagittal movements and a thigh with powerful musculature used during propulsion. In sum, the analyzed postcranial features are consistent with the limb morphology of ambulatory rodents, but with faculty to dig or swim. The sedimentary evidence of the localities in which fossils of neoepiblemids have been found suggests that these rodents lived in wet and water-related environments (near swamps, lakes, and/or rivers).

Sirenians are placental mammals that comprise the extant manatees (Trichechus manatus, T. inunguis, and T. senegalensis) and dugongs (Dugong dugon). Since the late 19th century, cranial endocasts of extinct sirenians have been employed to study the neurological evolution of these mammals during the Cenozoic. Here, we analyzed the endocranial morphology of Dioplotherium cf. allisoni (MPEG 63–V) from the middle Miocene of South America to gain insights on brain morphology and encephalization. This sirenian was ca. three meters long, weighed approximately 800 kg, and inhabited coastal marine environments of northern Brazil 14.2 to 12.7 million years ago. The cranial endocast of this animal is lissencephalic, with two smooth hemispheres divided by a deep median sulcus and presenting a weakly marked Sylvian fissure separating frontal and temporal lobes. The olfactory bulbs are small (compared to Paleogene stem sirenians as well as terrestrial mammals), and the optic nerves were thin but long. The sphenorbital fissure and mandibular canal are bulky, indicating the presence of large sensory trigeminal components that innervate the facial region, which was presumably covered by perioral bristles and facial hairs used to feed and explore the environment. The encephalization quotient is 0.36 (Jerison’s EQ) and 0.34 (Manger’s EQ). Ancestral character state reconstruction suggests that, despite an overall slight increase in the degree of encephalization of sirenians, except for the extant Dugong dugon, other analyzed taxa present values below 0.5. This is in accordance with previous studies that have maintained that sirenians have a relatively small brain size compared to other tethytherians, perhaps associated with their lifestyle.

Traversodontidae is a group of Triassic herbivorous/omnivorous cynodonts that represents the most diversified lineage within Cynognathia. In southern Brazil, a rich fossil record of late Middle/mid-Late Triassic cynodonts has been documented, with Exaeretodon riograndensis Abdala, Barberena, and Dornelles, 2002 and Siriusgnathus niemeyerorum Pavanatto et al., 2018 representing two abundant and well-documented traversodontids. The present study provides a comparative analysis of the morphology of the nasal cavity, nasal recesses, nasolacrimal duct, and maxillary canals of both species using computed tomography, highlighting the changes that occurred in parallel to the origin of mammaliaforms. Our results show that there were no ossified turbinals or a cribriform plate delimiting the posterior end of the nasal cavity, suggesting these structures were probably cartilaginous as in nonmammaliaform cynodonts. Both species show lateral ridges on the internal surface of the roof of the nasal cavity, but the median ridge for the attachment of a nasal septum is absent. Exaeretodon riograndensis and S. niemeyerorum show recesses on the dorsal region of the nasal cavity, which increase the volume of the nasal cavity, potentially enhancing the olfactory chamber and contributing to the sense of smell. On the lateral sides of the nasal cavity, the analyzed taxa show a well-developed maxillary recess. Although E. riograndensis and S. niemeyerorum have roughly similar nasal cavities, in the former taxon, the space between the left and right dorsal recesses of the nasal cavity is uniform along its entire extension, whereas this space narrows posteriorly in S. niemeyerorum. Finally, the nasolacrimal duct of S. niemeyerorum is more inclined anteroposteriorly than in E. riograndensis.

Here we described a new specimen (UFRGS-PV-0543-T) of the non-mamaliaform cynodont Prozostrodon brasiliensis, collected in the Faixa Nova locality (Santa Maria City, State of Rio Grande do Sul, Brazil), which is referred to the Upper Triassic, Hyperodapedon Assemblage Zone. The new specimen includes a portion of the cranium (fragmented nasals, lacrimals, prefrontals, frontals, palatines, vomer, and fragments of the right premaxilla, left maxilla, and pterygoid), preserving the natural endocast of the nasal cavity, and a fragmented right dentary. The specimen is assigned to P. brasiliensis based on the absence of the postorbital bar, the shape and extension of the snout, the height of the horizontal ramus of the dentary, the position of the Meckelian groove, the morphology of the last postcanine (the only one with the crown partially preserved), and fitting size. The natural endocast is composed of sediment that filled in the nasal cavity. On the dorsal surface of the endocast, there is a longitudinal median sulcus formed by the median bony ridge. Laterally to this median sulcus, there is a longitudinal sulcus on each side formed by the lateral crests. The vomer is low and robust, tapering anteriorly and showing a dorsal groove along its entire length. Other aspects of the endocranial anatomy of UFRGS-PV-0543-T, including wide olfactory region and marked oval-shaped olfactory bulbs, are similar to those of other Late Triassic probainognathian cynodonts. Neste trabalho, descrevemos um novo espécime (UFRGS-PV-0543-T) do cinodonte não-mamaliaforme Prozostrodon brasiliensis, coletado na localidade Faixa Nova (Santa Maria, Rio Grande do Sul, Brasil), Triássico Superior, Zona de Associação de Hyperodapedon. O novo espécime é representado por uma porção do crânio (incluindo nasais fragmentados, lacrimais, pré-frontais, frontais, palatinos, vômer, e fragmentos da pré-maxila direita, maxila esquerda e pterigoide), que preserva o molde endocraniano natural da cavidade nasal, e um dentário direito fragmentado. O espécime é atribuído a P. brasiliensis baseado na ausência da barra pós-orbital, a forma e extensão do rostro, a altura do ramo horizontal do dentário, a posição do sulco Meckeliano, a morfologia do último pós-canino (o único com a coroa parcialmente preservada), e tamanho similar ao holótipo. O molde endocraniano natural é formado pelo sedimento que preencheu a cavidade nasal durante o processo de fossilização. Sobre a superfície dorsal desse molde, existem três sulcos longitudinais originados pela crista mediana e cristas laterais, presentes na superfície interna dos ossos que formam o teto da cavidade nasal. O vômer é baixo e robusto, afinado anteriormente e apresenta um sulco dorsal ao longo de todo o seu comprimento. Outros aspectos da anatomia endocraniana de UFRGS-PV-0543-T, incluindo ampla região olfatória e bulbos olfatórios ovais marcados, são semelhantes aos de outros cinodontes probainognátios do Triássico Superior. Fil: Kerber, Leonardo. Universidade Federal de Santa Maria; Brasil Fil: Martinelli, Agustín Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Gusmão Rodrigues, Pablo. Universidade Federal do Rio Grande do Sul; Brasil Fil: Ribeiro, Ana Maria. Museu de Ciencias Naturais; Brasil Fil: Schultz, Cesar Leandro. Universidade Federal do Rio Grande do Sul; Brasil Fil: Bento Soares, Marina. Universidade Federal do Rio de Janeiro; Brasil

Dicynodonts represent a speciose clade of non-mammalian synapsids that lived from the middle Permian to the Late Triassic, exhibiting a Pangaean distribution. The South American Norian fossil recor...

Our knowledge on the anatomy of the first dinosaurs (Late Triassic, 235–205 Ma) has drastically increased in the last years, mainly due to several new findings of exceptionally well‐preserved specimens. Nevertheless, some structures such as the neurocranium and its associated structures (brain, labyrinth, cranial nerves, and vasculature) remain poorly known, especially due to the lack of specimens preserving a complete and articulated neurocranium. This study helps to fill this gap by investigating the endocranial cavity of one of the earliest sauropodomorphs, Buriolestes schultzi, from the Upper Triassic (Carnian—c. 233 Ma) of Brazil. The endocranial anatomy of this animal sheds light on the ancestral condition of the brain of sauropodomorphs, revealing an elongated olfactory tract combined to a relatively small pituitary gland and well‐developed flocculus of the cerebellum. These traits change drastically across the evolutionary history of sauropodomorphs, reaching the opposite morphology in Jurassic times. Furthermore, we present here the first calculations of the Reptile Encephalization Quotient (REQ) for a Triassic dinosaur. The REQ of B. schultzi is lower than that of Jurassic theropods, but higher than that of later sauropodomorphs. The combination of cerebral, dental, and postcranial data suggest that B. schultzi was an active small predator, able to track moving prey.

Among the several fossils of South American tayassuids, it is remarkable the presence of a well-preserved skull from southern Brazil (Chui Creek, Santa Vitoria do Palmar, Santa Vitoria Formation). ...

Dicynodontia is a major clade of terrestrial tetrapods that greatly diversified during the Permian and Triassic periods, reaching a worldwide distribution. In this study, the endocranial cavity of the Brazilian Permian dicynodont Rastodon procurvidens is described based on a digital endocast obtained using digital imaging (X-ray computed tomography) and 3D modeling. It was possible to reconstruct the brain, olfactory bulbs, inner ear, some neurovascular canals, cranial nerves, the nasal cavity, and the maxillary recesses. The endocast of R. procurvidens preserves a typical plesiomorphic morphology of non-mammaliaform therapsids, being predominantly tubular and displaying a relatively short and robust hindbrain. Encephalization quotients (EQs) were calculated for R. procurvidens, resulting in EQs of 0.09 ± 0.03 and 0.13 ± 0.05 (Jerison's EQ and Manger's EQ, respectively). Finally, some biological implications of the endocast morphology were inferred for R. procurvidens. Its inner ear is especially small, and its orientation implies a slightly downturned head posture in life. Furthermore, the presence of uncompressed maxillary recesses in R. procurvidens indicates a correlation between the enlargement of the recesses and the reduction of the tusks, also seen in other dicynodonts with reduced tusks.

In this work, new fossils of Hydrochoerinae rodents (Caviomorpha: Caviidae: Hydrochoerinae) from the Quaternary of the intertropical region of Brazil are described, almost 180 years after the first fossils of these animals were found in Lagoa Santa, Minas Gerais. The fossils studied herein were collected in caves of States of Bahia (Toca dos Ossos and Lapa dos Brejoes) and Minas Gerais (Lapa Vermelha cave, Lagoa Santa karst). The analyzed material is assigned to the extinct large rodent Neochoerus sulcidens and is composed of skull portion, upper and lower cheek teeth, mandible, humerus, innominate, femur, tibia, and calcaneus. The specimens were assigned to this taxon based on the presence of an M3 with 14 prisms; incisor alveolus reaching the pr. II do m2; anteriormost level of the palatine at the level of the Pr. II of the M2; and larger size than the living species. The p4 is mesiodistally longer than the m1 and m2, distinct from previous interpretations in which the mesiodistal length of the p4 of N. sulcidens would be smaller than the m2, indicating the presence of a variable character. Except for the differences in size, the postcranial bones of N. sulcidens are quite similar to H. hydrochaeris.

A new Upper Triassic fossiliferous outcrop, the Niemeyer Site, from the Santa Maria Supersequence (Parana Basin, Southern Brazil) is reported. The lithology found in this locality is consistent with that found in the Candelaria Sequence. The high prevalence of traversodontid cynodonts in this site is particularly notable, with collected specimens mostly composed of isolated bones and fragmentary specimens, but also including well-preserved skulls and mandibles. Probainognathian cynodonts and archosauromorphs are also present, but they are rare in comparison. There is a predominance of Voorhies Group III (Group III > Group I > Group II) for the specimens so far collected. These data, as well as the sedimentary data of the outcrop, indicate a mostly autochthonous fossiliferous assemblage. Some specimens display evidence of ichnological activity of invertebrate scavengers (bone alteration comprising small tubules, channels and isolated boreholes). A remarkable aspect of this site is the presence of a new traversodontid cynodont closely related to Exaeretodon. Although similar to the former taxon, the new taxonomic unit shows a unique combination of several craniodental features not present in other cynodonts. Given that no traversodontids are recorded in the uppermost levels of the Candelaria Sequence, this site is likely placed in the lower levels of this unit, with the fauna suggesting a Carnian age.

Tanystropheidae is a clade of early archosauromorphs with a reported distribution ranging from the Early to the Late Triassic of Asia, Europe, and North America. Although some specimens with possible tanystropheid affinities from the Lower Triassic beds of Brazil have been previously attributed to “Protorosauria”, little is known about the tanystropheid record in Gondwana. Here, two new and one previously reported specimen from the Sanga do Cabral Formation (Induan–Olenekian) of Brazil are described and interpreted as ?Tanystropheidae. These records, together with other tetrapods previously reported for the Sanga do Cabral Formation, increase the knowledge of the biotic diversification during the beginning of the Triassic. This contribution reinforces that the archosauromorph diversification occurred shortly after the Permo-Triassic extinction, making the Sanga do Cabral Formation an important unit for the study of early Mesozoic faunas.

Recently, the morphology and encephalization of the brain endocast of the Triassic non-mammaliaform probainognathian cynodont Riograndia guaibensis were studied. Here, we analyzed the brain endocast of an additional specimen of this species. The new endocast shows well-defined olfactory bulbs and a median sulcus dividing the hemispheres, traits that were not clearly observed in the first studied specimen. Encephalization quotients were also calculated, revealing similar values to other non-mammaliaform cynodonts and lower than those of the first analyzed specimen. The analyzed cranium is slightly larger than the first studied one and may represent an advanced ontogenetic stage. Hence, these differences may be related to the intraspecific variation of this cynodont or alternatively, to the preservation of each specimen. Fil: Kerber, Leonardo. Universidade Federal de Santa Maria; Brasil Fil: Ferreira, José Darival. Universidade Federal de Santa Maria; Brasil Fil: Fonseca, Pedro Henrique M.. Universidade Federal do Rio Grande do Sul; Brasil Fil: Franco, Arymatheia. Universidade Federal de Santa Maria; Brasil Fil: Martinelli, Agustín Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Soares, Marina Bento. Universidade Federal do Rio Grande do Sul; Brasil. Universidade Federal do Rio de Janeiro; Brasil Fil: Ribeiro, Ana Maria. Universidade Federal do Rio Grande do Sul; Brasil

In this contribution, we described a new fossil of a Pleistocene Tayassuidae from northern Brazil. The specimen is a left dentary with molars assigned to cf. Pecari tajacu recovered from an outcrop of the Rio Madeira Formation, State of Rondônia, Brazil. It represents the first Pleistocene fossil of this clade with stratigraphic provenance in the Amazon region of Brazil. This record contributes to the knowledge on the paleofauna of Rio Madeira Formation as well as extend the past geographic distribution of peccaries in South America.

Mylododontidae (Xenarthra: Folivora) includes ground sloths of medium to large size. Lestodon armatus is a mylodontid that have been found in Pleistocene fossiliferous deposits of South America, with most of its records at the southern portion of the continent. Here, we reported a new specimen assigned to this species recovered from a Quaternary deposit in Caçapava do Sul, southern Brazil. The specimen is composed of cranial fragments, vertebrae, articulated hind limb and pes, as well as other post-cranial elements. We described the post-cranial morphology of this specimen, including some elements not yet described for this species, such as the ossified meniscus, cyamo-fabella, and the fusion of the tibia and fibula. The new record contributes to the knowledge on the anatomy of L. armatus as well as to the study of the diversity of the extinct mammalian fauna from southern Brazil.

The fusion of the sacrum occurs in the major dinosaur lineages, i.e. ornithischians, theropods, and sauropodomorphs, but it is unclear if this trait is a common ancestral condition, or if it evolved independently in each lineage, or even how or if it is related to ontogeny. In addition, the order in which the different structures of the sacrum are fused, as well as the causes that lead to this co-ossification, are poorly understood. Herein, we described the oldest record of fused sacral vertebrae within dinosaurs, based on two primordial sacral vertebrae from the Late Triassic of Candelaria Sequence, southern Brazil. We used computed microtomography (micro-CT) to analyze the extent of vertebral fusion, which revealed that it occurred only between the centra. We also assessed the occurrence of sacral fusion in Dinosauria and close relatives. The degree of fusion observed in representatives of the major dinosaur lineages suggested that there may be a sequential pattern of fusion of the elements of the sacrum, more clearly observed in Sauropodomorpha. Our analyses suggest that primordial sacral vertebrae fuse earlier in the lineage (as seen in Norian sauropodomorphs). Intervertebral fusion is observed to encompass progressively more vertebral units as sauropodomorphs evolve, reaching up to five or more fully fused sacrals in Neosauropoda. Furthermore, the new specimen described here indicates that the fusion of sacral elements occurred early in the evolution of dinosaurs. Factors such as ontogeny and the increase in body size, combined with the incorporation of vertebrae to the sacrum may have a significant role in the process and in the variation of sacral fusion observed.

The Pliocene–Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus, Schizodon, Amblydoras, Scorpiodoras, and the pipesnake Anilius scytale, all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86Sr/88Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years.

A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.

After the Permo-Triassic mass extinction, the archosauromorph fossil record is comparatively abundant and ecologically diverse. Among early archosauromorphs, tanystropheids gained considerable attention due to the presence of extreme skeletal adaptations in response to sometimes overspecialized lifestyles. The origin and early radiation of Tanystropheidae, however, remains elusive. Here, a new Early Triassic archosauromorph is described and phylogenetically recovered as the sister-taxon of Tanystropheidae. The new specimen, considered a new genus and species, comprises a complete posterior limb articulated with pelvic elements. It was recovered from the Sanga do Cabral Formation (Sanga do Cabral Supersequence, Lower Triassic of the Paraná Basin, Southern Brazil), which has already yielded a typical Early Triassic vertebrate assemblage of temnospondyls, procolophonoids, and scarce archosauromorph remains. This new taxon provides insights on the early diversification of tanystropheids and represents further evidence for a premature wide geographical distribution of this clade. The morphology of the new specimen is consistent with a terrestrial lifestyle, suggesting that this condition was plesiomorphic for Tanystropheidae.

A recurrent aspect of the fossil record is the observation of a disproportionate number of specimens or individuals of a single taxon in some deposits, which is stated as dominance. Commonly, the dominance is explained as the result of catastrophic or short-term mass death events or are proxies for palaeoecological inferences regarding gregariousness. However, taphonomic, stratigraphic and chronologic analyses of fossiliferous deposits have shown that this is not always true. To contribute to the study of dominance in fossil assemblages, we describe a probable Quaternary skeletal accumulation dominated by the extant gregarious rock-dwelling rodent Kerodon rupestris recovered from Sumidouro do Sansao, a 65 m deep pitfall cave in northeast Brazil, and discuss the palaeoecological implications of our findings. We provide taxonomic identification, taphonomic analyses, and chronological assessment. Besides K. rupestris (minimum number of individuals, MNI = 35), we recorded three taxonomic groups, that are the ground sloth Catonyx cuvieri (MNI = 1), the anteater Tamandua tetradactyla (MNI = 1), and the cougar Puma concolor (MNI = 1). The taphonomic analysis of the K. rupestris remains supports the idea that entrapment of individuals was the main process of bone accumulation and that the death of cave inhabitants followed by short transport to the main hall possibly occurred. Kerodon rupestris remains persisted on the surface of the cave deposit for different time spans and were exposed to fragmentation, weathering, invertebrate boring and encrustation inside the cave environment. Direct dating suggests differences in the ages obtained and intermittent deposition of the individuals inside the cave. It highlights the influence of taphonomic controls on gregarious taxa, such as K. rupestris, towards dominating attritional time-averaged assemblages. Furthermore, it demonstrates that such assemblages do not necessarily support inferences about single event mortality and gregariousness of the dominant taxon.