Youngina (Permian reptile) high-frequency hearing + identifying injury paleopathologies + Cretaceous Tarrant Formation vertebrates + element clues to paleoenvironments
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Ben Creisler
Dec 22, 2025, 2:08:41 PM12/22/25
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Ben Creisler
Some recent papers:
Kelsey M. Jenkins, Rachel C. Fleming, Juan D. Daza & Hans-Dieter Sues (2025)
Evidence for high-frequency hearing in a Permian stem reptile
Nature Communications (unedited preprint)
doi: https://doi.org/10.1038/s41467-025-66956-6
https://www.nature.com/articles/s41467-025-66956-6
High-frequency hearing evolved in most amniote lineages in the Permian and Triassic. However, for reptiles, the evolutionary history of hearing is more elusive. Some have suggested that tympanic hearing evolved independently in each major lineage of reptile, largely based on gross observations of the stapes and outer ear region of fossils. On that basis, it was postulated that many Permian stem reptiles could not hear high frequencies. However, this hypothesis lacks quantitative support. To our knowledge, biomechanical analyses have not previously been conducted to determine the capacity for hearing in stem reptiles. Here, we conduct functional and morphometric analyses of the reptilian stapes including fossil data. Using harmonic response analyses, we demonstrate that the stapes of the stem reptile Youngina capensis could be displaced proximodistally at values similar to tympanic squamates. Additionally, Y. capensis is predicted to possess a tympanum based on a flexible discriminant analysis, while early-diverging stem reptiles are classified as low-frequency bone conductors. We show that hearing was facilitated by the formation of the annular ligament, improving stapedial movement, in addition to the evolution of a slender stapes and tympanum. Our results suggest that relatively high-frequency hearing was present in the common ancestor of reptiles, originating by the late Permian.
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Maximilian Scott, Julia A. Gamble, Caleb Marshall Brown, Kirstin S. Brink
Injuries in deep time: interpreting competitive behaviours in extinct reptiles via palaeopathology
Biological Reviews (advance online publication)
doi: https://doi.org/10.1002/brv.70116
https://onlinelibrary.wiley.com/doi/10.1002/brv.70116
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/brv.70116
For over a century, palaeopathology has been used as a tool for understanding evolution, disease in past communities and populations, and to interpret behaviour of extinct taxa. Physical traumas in particular have frequently been the justification for interpretations about aggressive and even competitive behaviours in extinct taxa. However, the standards used in these interpretations have been inconsistent and occasionally questionable, and knowledge of extant reptile pathology is limited. Interpretations about the timelines and causes of unhealed bone damage are unreliable, and so behavioural implications from these marks are dubious. Even in the case of tooth marks, perimortem damage can be difficult to distinguish from postmortem alteration. In this review, methods from the anthropological sciences are adapted for the purposes of palaeontology, especially in establishing a new framework to distinguish antemortem traumatic damage from other similarly presenting features like sediment encrustation, postmortem damage/taphonomic features, variants of anatomical features, and non-traumatic palaeopathologies. Even in cases where traumatic palaeopathologies are accurately macroscopically identified, noting isolated incidences may not provide sufficient evidence to interpret behaviour at any taxonomic level. Future research directions in modern reptile pathology are proposed to improve the efficacy of traumatic palaeopathologies as a tool in interpreting extinct reptile behaviours.
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Felipe M.S. Cardia, José Vicente E. Bernardi, Carlos Eduardo M. Oliveira, Marco B. Andrade, Max C. Langer, Sandra A.S. Tavares, Fabiano V. Iori, William R. Nava, Thiago S. Marinho, Luiz Carlos B. Ribeiro, Jurandir R. Souza & Rodrigo M. Santucci (2025)
Mercury concentration: A new window into ancient diets and trophic levels in vertebrate paleontology
Chemical Geology 123218
doi: https://doi.org/10.1016/j.chemgeo.2025.123218
https://www.sciencedirect.com/science/article/abs/pii/S0009254125006084
Highlights
Hg levels in Bauru Group vertebrate fossils indicate their trophic positions.
Some sphagesaurids show low Hg levels equivalent to herbivores.
Baurusuchids and abelisaurids were Bauru Group top predators.
Abstract
Direct evidence about feeding habits and trophic levels of extinct species is scarce in the fossil record. Typically, such information is based on geochemistry, stomach contents, anatomy, and, whenever possible, comparison with living counterparts. Despite the challenges involved, such reconstructions are vital for understanding the structure of past ecosystems. Here, we propose a novel geochemical approach in paleontology that uses total mercury concentration (THg) in fossil vertebrate tissues (bones and tooth enamel) and its bioaccumulation and biomagnification properties as geochemical indicators for the inference of feeding habits and trophic levels. Thin section and X-ray diffractometry (XRD) revealed that THg values found in bioapatite from the diverse and well-preserved fossil vertebrates of the Upper Cretaceous Bauru Group (Brazil) are not altered by diagenetic processes. The results show that each vertebrate group analyzed (e.g., fishes, turtles, amphibians, crocodylomorphs, avian, and non-avian dinosaurs) are characterized by different THg concentrations (ranging from 1.66 to 15 ng.g−1 Hg). Notably, similar values were found in fossils of the same taxonomic group regardless of their geological unit of origin. More importantly, taxa with different feeding habits were positioned at different trophic levels based on the bioaccumulation and biomagnification of Hg. Reliable Hg analyses in fossils require confirming that bones are free from diagenetic contamination that may artificially elevate their Hg concentrations.
=====
Free pdf:
Kelsey M. Jenkins, Rachel C. Fleming, Juan D. Daza & Hans-Dieter Sues (2025)
Evidence for high-frequency hearing in a Permian stem reptile
Nature Communications (unedited preprint)
doi: https://doi.org/10.1038/s41467-025-66956-6
https://www.nature.com/articles/s41467-025-66956-6
High-frequency hearing evolved in most amniote lineages in the Permian and Triassic. However, for reptiles, the evolutionary history of hearing is more elusive. Some have suggested that tympanic hearing evolved independently in each major lineage of reptile, largely based on gross observations of the stapes and outer ear region of fossils. On that basis, it was postulated that many Permian stem reptiles could not hear high frequencies. However, this hypothesis lacks quantitative support. To our knowledge, biomechanical analyses have not previously been conducted to determine the capacity for hearing in stem reptiles. Here, we conduct functional and morphometric analyses of the reptilian stapes including fossil data. Using harmonic response analyses, we demonstrate that the stapes of the stem reptile Youngina capensis could be displaced proximodistally at values similar to tympanic squamates. Additionally, Y. capensis is predicted to possess a tympanum based on a flexible discriminant analysis, while early-diverging stem reptiles are classified as low-frequency bone conductors. We show that hearing was facilitated by the formation of the annular ligament, improving stapedial movement, in addition to the evolution of a slender stapes and tympanum. Our results suggest that relatively high-frequency hearing was present in the common ancestor of reptiles, originating by the late Permian.
=====
Free pdf:
Maximilian Scott, Julia A. Gamble, Caleb Marshall Brown, Kirstin S. Brink
Injuries in deep time: interpreting competitive behaviours in extinct reptiles via palaeopathology
Biological Reviews (advance online publication)
doi: https://doi.org/10.1002/brv.70116
https://onlinelibrary.wiley.com/doi/10.1002/brv.70116
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/brv.70116
For over a century, palaeopathology has been used as a tool for understanding evolution, disease in past communities and populations, and to interpret behaviour of extinct taxa. Physical traumas in particular have frequently been the justification for interpretations about aggressive and even competitive behaviours in extinct taxa. However, the standards used in these interpretations have been inconsistent and occasionally questionable, and knowledge of extant reptile pathology is limited. Interpretations about the timelines and causes of unhealed bone damage are unreliable, and so behavioural implications from these marks are dubious. Even in the case of tooth marks, perimortem damage can be difficult to distinguish from postmortem alteration. In this review, methods from the anthropological sciences are adapted for the purposes of palaeontology, especially in establishing a new framework to distinguish antemortem traumatic damage from other similarly presenting features like sediment encrustation, postmortem damage/taphonomic features, variants of anatomical features, and non-traumatic palaeopathologies. Even in cases where traumatic palaeopathologies are accurately macroscopically identified, noting isolated incidences may not provide sufficient evidence to interpret behaviour at any taxonomic level. Future research directions in modern reptile pathology are proposed to improve the efficacy of traumatic palaeopathologies as a tool in interpreting extinct reptile behaviours.
=====
=====
Aaron E. Johnson, Michael J. Polcyn & Kenshu Shimada (2025)
Late Cretaceous vertebrate assemblage of the Tarrant Formation (middle Cenomanian) of the Eagle Ford Group in Texas, USA
Historical Biology (advance online publication)
https://doi.org/10.1080/08912963.2025.2580946
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2580946
The Tarrant Formation is stratigraphically the lowermost unit of the Upper Cretaceous Eagle Ford Group in Texas, U.S.A. and consists of sandstone formed near the East Texas Embayment of the Late Cretaceous Western Interior Seaway during the middle Cenomanian (ca. 95.78 Ma). We examined the taxonomic composition of vertebrate fossils from the Tarrant Formation based on specimens acquired through surface collecting and bulk sampling from three localities within Tarrant County, Texas. The specimens collected in this study, combined with the published record, reveal a diverse vertebrate assemblage that consists of a minimum of 24 vertebrate taxa, comprising at least eight chondrichthyans (Ptychodus, Microcarcharias, Cretodus, Cretoxyrhina, Cretalamna, and three species of Squalicorax), 12 bony fishes (Protosphyraena, Plethodidae, two pycnodonts, two pachyrhizodontids, two ichthyodectiforms, two enchodontids, and two indeterminate taxa), and four tetrapod taxa (e.g. two plesiosaurs, dolichosaurid, and pterosaur). These taxa occupy a variety of trophic regimes, including piscivorous, durophagous, and opportunistic or scavenging taxa. As the first collective survey of the vertebrates from the Tarrant Formation of Texas, this study offers new insights into the palaeoecology of this area during the middle Cenomanian, a critical point in the early development of the Western Interior Seaway and the East Texas Embayment.
Late Cretaceous vertebrate assemblage of the Tarrant Formation (middle Cenomanian) of the Eagle Ford Group in Texas, USA
Historical Biology (advance online publication)
https://doi.org/10.1080/08912963.2025.2580946
https://www.tandfonline.com/doi/full/10.1080/08912963.2025.2580946
The Tarrant Formation is stratigraphically the lowermost unit of the Upper Cretaceous Eagle Ford Group in Texas, U.S.A. and consists of sandstone formed near the East Texas Embayment of the Late Cretaceous Western Interior Seaway during the middle Cenomanian (ca. 95.78 Ma). We examined the taxonomic composition of vertebrate fossils from the Tarrant Formation based on specimens acquired through surface collecting and bulk sampling from three localities within Tarrant County, Texas. The specimens collected in this study, combined with the published record, reveal a diverse vertebrate assemblage that consists of a minimum of 24 vertebrate taxa, comprising at least eight chondrichthyans (Ptychodus, Microcarcharias, Cretodus, Cretoxyrhina, Cretalamna, and three species of Squalicorax), 12 bony fishes (Protosphyraena, Plethodidae, two pycnodonts, two pachyrhizodontids, two ichthyodectiforms, two enchodontids, and two indeterminate taxa), and four tetrapod taxa (e.g. two plesiosaurs, dolichosaurid, and pterosaur). These taxa occupy a variety of trophic regimes, including piscivorous, durophagous, and opportunistic or scavenging taxa. As the first collective survey of the vertebrates from the Tarrant Formation of Texas, this study offers new insights into the palaeoecology of this area during the middle Cenomanian, a critical point in the early development of the Western Interior Seaway and the East Texas Embayment.
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Aishee Sanyal & Sanghamitra Ray (2025)
New insights on early diagenesis and palaeoenvironment of the Late Triassic bonebeds of India: evidence from rare earth element concentrations in fossil vertebrates
Gondwana Research (advance online publication)
doi: https://doi.org/10.1016/j.gr.2025.11.020
https://www.sciencedirect.com/science/article/abs/pii/S1342937X25003752
Highlights
Geochemical study of four contemporary bonebeds in the Upper Triassic Tiki Formation.
XRD and IC-PMS analysis were carried out to acquire geochemical data.
Rare earth element concentrations revealed the fossilization pathways of the bonebeds.
Abstract
This first comprehensive geochemical investigation of vertebrate fossils from India focuses on mass death assemblages recovered from four contemporaneous bonebeds in the Upper Triassic Tiki Formation, India. The study encompasses three extinct tetrapod taxonomic groups, namely the metoposaurids, phytosaurs and rhynchosaurs that co-existed, occupied different life habits and proliferated on the Tiki landscape. Geochemical signals including high crystallinity indices with low variability, similar patterns of Post-Archean Australian Shale-normalised mean rare earth element concentrations, considerable overlapping of convex hull polygons, and consistent enrichment in middle rare earth elements suggest similar early diagenetic palaeoenvironments for the four Tiki bonebeds. Such enrichment in middle rare earth elements is seen because of the presence of iron oxide within a terrestrial well-oxygenated fluvial setting that prevailed during fossilisation. The burial was a single-phase event, likely caused by a major flooding event, irrespective of whether the fossil accumulation was time-averaged, attritional or catastrophic. Differences in mean rare earth element concentrations in the taxonomic groups may have resulted from variation in their infiltration that was influenced by bone density which in-turn was influenced by contrasts in lifestyle. A positive europium anomaly in all specimens suggests localised reducing or anaerobic conditions resulting from autolytic degradation of the tissues at the time of early diagenesis. Studied specimens exhibited both positive and negative cerium anomalies that signify variations in the duration of subaerial exposure prior to burial, weathering stages and burial depth. The study helped in delineating the early diagenetic palaeoenvironments and reconstructing fossilisation pathways of the four Late Triassic bonebeds and highlights the significance of understanding geochemical signals in fossil bones.
=====
New insights on early diagenesis and palaeoenvironment of the Late Triassic bonebeds of India: evidence from rare earth element concentrations in fossil vertebrates
Gondwana Research (advance online publication)
doi: https://doi.org/10.1016/j.gr.2025.11.020
https://www.sciencedirect.com/science/article/abs/pii/S1342937X25003752
Highlights
Geochemical study of four contemporary bonebeds in the Upper Triassic Tiki Formation.
XRD and IC-PMS analysis were carried out to acquire geochemical data.
Rare earth element concentrations revealed the fossilization pathways of the bonebeds.
Abstract
This first comprehensive geochemical investigation of vertebrate fossils from India focuses on mass death assemblages recovered from four contemporaneous bonebeds in the Upper Triassic Tiki Formation, India. The study encompasses three extinct tetrapod taxonomic groups, namely the metoposaurids, phytosaurs and rhynchosaurs that co-existed, occupied different life habits and proliferated on the Tiki landscape. Geochemical signals including high crystallinity indices with low variability, similar patterns of Post-Archean Australian Shale-normalised mean rare earth element concentrations, considerable overlapping of convex hull polygons, and consistent enrichment in middle rare earth elements suggest similar early diagenetic palaeoenvironments for the four Tiki bonebeds. Such enrichment in middle rare earth elements is seen because of the presence of iron oxide within a terrestrial well-oxygenated fluvial setting that prevailed during fossilisation. The burial was a single-phase event, likely caused by a major flooding event, irrespective of whether the fossil accumulation was time-averaged, attritional or catastrophic. Differences in mean rare earth element concentrations in the taxonomic groups may have resulted from variation in their infiltration that was influenced by bone density which in-turn was influenced by contrasts in lifestyle. A positive europium anomaly in all specimens suggests localised reducing or anaerobic conditions resulting from autolytic degradation of the tissues at the time of early diagenesis. Studied specimens exhibited both positive and negative cerium anomalies that signify variations in the duration of subaerial exposure prior to burial, weathering stages and burial depth. The study helped in delineating the early diagenetic palaeoenvironments and reconstructing fossilisation pathways of the four Late Triassic bonebeds and highlights the significance of understanding geochemical signals in fossil bones.
=====
Felipe M.S. Cardia, José Vicente E. Bernardi, Carlos Eduardo M. Oliveira, Marco B. Andrade, Max C. Langer, Sandra A.S. Tavares, Fabiano V. Iori, William R. Nava, Thiago S. Marinho, Luiz Carlos B. Ribeiro, Jurandir R. Souza & Rodrigo M. Santucci (2025)
Mercury concentration: A new window into ancient diets and trophic levels in vertebrate paleontology
Chemical Geology 123218
doi: https://doi.org/10.1016/j.chemgeo.2025.123218
https://www.sciencedirect.com/science/article/abs/pii/S0009254125006084
Highlights
Hg levels in Bauru Group vertebrate fossils indicate their trophic positions.
Some sphagesaurids show low Hg levels equivalent to herbivores.
Baurusuchids and abelisaurids were Bauru Group top predators.
Abstract
Direct evidence about feeding habits and trophic levels of extinct species is scarce in the fossil record. Typically, such information is based on geochemistry, stomach contents, anatomy, and, whenever possible, comparison with living counterparts. Despite the challenges involved, such reconstructions are vital for understanding the structure of past ecosystems. Here, we propose a novel geochemical approach in paleontology that uses total mercury concentration (THg) in fossil vertebrate tissues (bones and tooth enamel) and its bioaccumulation and biomagnification properties as geochemical indicators for the inference of feeding habits and trophic levels. Thin section and X-ray diffractometry (XRD) revealed that THg values found in bioapatite from the diverse and well-preserved fossil vertebrates of the Upper Cretaceous Bauru Group (Brazil) are not altered by diagenetic processes. The results show that each vertebrate group analyzed (e.g., fishes, turtles, amphibians, crocodylomorphs, avian, and non-avian dinosaurs) are characterized by different THg concentrations (ranging from 1.66 to 15 ng.g−1 Hg). Notably, similar values were found in fossils of the same taxonomic group regardless of their geological unit of origin. More importantly, taxa with different feeding habits were positioned at different trophic levels based on the bioaccumulation and biomagnification of Hg. Reliable Hg analyses in fossils require confirming that bones are free from diagenetic contamination that may artificially elevate their Hg concentrations.
=====
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