Eupelycosaurs and Kungurian extinctions in Permian + salamandrids in Late Cretaceous of Europe + putative lacertoid tracks from the Lower Cretaceous Botucatu Formation (free pdfs)
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Ben Creisler
Jun 8, 2026, 2:31:35 PM (3 days ago) Jun 8
to DinosaurMa...@googlegroups.com
Ben Creisler
Recent tetrapod papers:
Free pdf:
Loredana Macaluso, Olivier Jansen, Xavier Valentin, Jules D. Walter, Olga Otero, Romain Amiot & Geraldine Garcia (2026)
New fossil evidence from the Late Cretaceous of Europe (southern France) deepens the origin of Salamandridae (Urodela) and refines the biogeography of the family
Scientific Reports 16: 16567
doi: https://doi.org/10.1038/s41598-026-44690-3
https://link.springer.com/article/10.1038/s41598-026-44690-3
Salamandrids are today the most diverse family of salamanders of the Palearctic, including 146 species and 22 genera. The oldest fossil occurrences of the group are so far dated to the Paleocene (around 60 Myr ago), except for an isolated vertebra in the late Maastrichtian of Spain, although molecular studies place the origin of the group earlier, in the Late Cretaceous. New findings from the Upper Cretaceous of France fill this stratigraphic gap, significantly predating the previous oldest fossil occurrence of the group by 10 Ma. The material includes isolated vertebrae from four localities with an age spanning from the late Campanian to the late Maastrichtian, which can be straight-forwardly attributed to Salamandridae thanks to the type of ossification of the anterior condyle. The material from Les Pennes-Mirabeau and La Neuve can be referred to Koalliella sp., which was found in Paleocene deposits of other European localities. The same referral is only tentative in the case of the other two localities (Vérane, Champ-Garimond), due to their uncompleteness. New divergence timings for salamandrids are estimated based on the new stratigraphic ranges and on the recently recovered phylogenetic position of early salamandrids. Our data strongly support a European origin of salamandrids and biogeographic implications are discussed by combining the current distributions, the fossil record, and the new timing divergence estimates. Our results notably strengthen previous biogeographic hypothesis based on the Cenozoic record, supporting three dispersal events from Europe: the North American Notophthalmus and Taricha clades colonised the Nearctic before the Oligocene through Beringia, whereas the two clades of crocodile newts (Echinotriton and Tylototriton) and the modern Asian newts (e.g. Cynops) likely reached Southeastern Asia during the Oligocene. The regression of the Turgai Sea at the end of the Eocene is herein suggested as the main geographical driver of the dispersal events.
Murilo Andrade-Silva & Heitor Francischini (2026)
Reassessing putative lacertoid tracks from the Lower Cretaceous Botucatu Formation (Brazil): ichnotaxonomic ambiguities in an aeolian palaeodesert
Journal of South American Earth Sciences 181: 106154
doi: https://doi.org/10.1016/j.jsames.2026.106154
https://www.sciencedirect.com/science/article/abs/pii/S0895981126002063
Highlights
Reassessment of tetrapod tracks from the Botucatu palaeodesert.
Tracks lack diagnostic features for reliable ichnotaxonomic assignment.
Morphology strongly controlled by substrate and dune slope.
Extramorphological features mimic lacertoid track characteristics.
Aeolian conditions bias track preservation and interpretation.
Integration of taphonomy is essential in desert ichnology.
Abstract
The Lower Cretaceous Botucatu Formation (Paraná Basin, Brazil) preserves one of the largest erg systems in Gondwana, but lacks vertebrate body fossils, making trace fossils the only evidence of its terrestrial fauna. This study presents a reassessment of putative lacertoid tracks using photogrammetry and morphometric analyses. Four specimens were examined to refine their ichnotaxonomic identity and evaluate possible trackmakers. Most tracks are poorly preserved, appearing as shallow, oval depressions without diagnostic features such as digit impressions. Comparisons with lacertoid and crocodylomorph ichnotaxa reveal significant morphological and locomotor inconsistencies, including the absence of key lacertoid traits. Wide variation in pace angulation (68.09°–157.96°) and the presence of marginal expulsion rims indicate strong control by substrate properties and locomotion on dune slopes. These tracks cannot be confidently assigned to any ichnotaxon and are better interpreted as substrate-related artifacts. This study highlights the importance of integrating ichnotaxonomy with sedimentological and taphonomic analyses in desert ichnofaunas.
Free pdf:
Michel Laurin, Gilles Didier, Sylvain Richoz, Matteo Montagna and Evelyn Kustatscher (2026)
Kungurian extinctions in eupelycosaurs: a press–pulse event?
Paleobiology (advance online publication)
DOI: https://doi.org/10.1017/pab.2026.10102
https://www.cambridge.org/core/journals/paleobiology/article/kungurian-extinctions-in-eupelycosaurs-a-presspulse-event/1B887C4D4086821F4D28BA2B3AEEC95C
The fossil record offers a unique window into patterns of extinction and biodiversity recovery over deep time, and recent advances in analytical methods have significantly enhanced this research field. Our analysis of an updated dataset that includes 50 terminal taxa and 175 fossil occurrences of Ophiacodontidae, Edaphosauridae, and Sphenacodontidae (OES grade hereafter) using a recent implementation of the skyline fossilized birth–death model (FBD hereafter) confirms our previous conclusion that the OES grade diversified during the latter half of the Pennsylvanian but waned thereafter. However, our new results differ in several important points compared with our previous study (published in 2024). Notably, the transition between these two diversification regimes seems to have occurred earlier (at 298.9 Ma, at the Carboniferous/Permian transition), and it appears to have been marked by a moderate (0.527 survival probability), previously unreported extinction event. Also, the OES grade seems to have experienced a much more severe mass extinction event in the mid-Kungurian, with an estimated survival rate of only 0.113, which left very few surviving OES grade lineages. Climatic instability that started around the Carboniferous/Permian boundary and lasted throughout the Cisuralian, plausibly caused by intense volcanism of the Tarim Large Igneous Province and the Panjal Traps, may explain this pattern, which consists of a stagnating biodiversity followed by a brief, severe extinction event. This is reminiscent of the press–pulse model proposed by Arens and West in 2008, but if there was indeed an end-Carboniferous crisis, it could also be viewed as a new, more complex, pulse–press–pulse pattern.
=====
Michel Laurin, Gilles Didier, Sylvain Richoz, Matteo Montagna and Evelyn Kustatscher (2026)
Kungurian extinctions in eupelycosaurs: a press–pulse event?
Paleobiology (advance online publication)
DOI: https://doi.org/10.1017/pab.2026.10102
https://www.cambridge.org/core/journals/paleobiology/article/kungurian-extinctions-in-eupelycosaurs-a-presspulse-event/1B887C4D4086821F4D28BA2B3AEEC95C
The fossil record offers a unique window into patterns of extinction and biodiversity recovery over deep time, and recent advances in analytical methods have significantly enhanced this research field. Our analysis of an updated dataset that includes 50 terminal taxa and 175 fossil occurrences of Ophiacodontidae, Edaphosauridae, and Sphenacodontidae (OES grade hereafter) using a recent implementation of the skyline fossilized birth–death model (FBD hereafter) confirms our previous conclusion that the OES grade diversified during the latter half of the Pennsylvanian but waned thereafter. However, our new results differ in several important points compared with our previous study (published in 2024). Notably, the transition between these two diversification regimes seems to have occurred earlier (at 298.9 Ma, at the Carboniferous/Permian transition), and it appears to have been marked by a moderate (0.527 survival probability), previously unreported extinction event. Also, the OES grade seems to have experienced a much more severe mass extinction event in the mid-Kungurian, with an estimated survival rate of only 0.113, which left very few surviving OES grade lineages. Climatic instability that started around the Carboniferous/Permian boundary and lasted throughout the Cisuralian, plausibly caused by intense volcanism of the Tarim Large Igneous Province and the Panjal Traps, may explain this pattern, which consists of a stagnating biodiversity followed by a brief, severe extinction event. This is reminiscent of the press–pulse model proposed by Arens and West in 2008, but if there was indeed an end-Carboniferous crisis, it could also be viewed as a new, more complex, pulse–press–pulse pattern.
=====
Free pdf:
Loredana Macaluso, Olivier Jansen, Xavier Valentin, Jules D. Walter, Olga Otero, Romain Amiot & Geraldine Garcia (2026)
New fossil evidence from the Late Cretaceous of Europe (southern France) deepens the origin of Salamandridae (Urodela) and refines the biogeography of the family
Scientific Reports 16: 16567
doi: https://doi.org/10.1038/s41598-026-44690-3
https://link.springer.com/article/10.1038/s41598-026-44690-3
Salamandrids are today the most diverse family of salamanders of the Palearctic, including 146 species and 22 genera. The oldest fossil occurrences of the group are so far dated to the Paleocene (around 60 Myr ago), except for an isolated vertebra in the late Maastrichtian of Spain, although molecular studies place the origin of the group earlier, in the Late Cretaceous. New findings from the Upper Cretaceous of France fill this stratigraphic gap, significantly predating the previous oldest fossil occurrence of the group by 10 Ma. The material includes isolated vertebrae from four localities with an age spanning from the late Campanian to the late Maastrichtian, which can be straight-forwardly attributed to Salamandridae thanks to the type of ossification of the anterior condyle. The material from Les Pennes-Mirabeau and La Neuve can be referred to Koalliella sp., which was found in Paleocene deposits of other European localities. The same referral is only tentative in the case of the other two localities (Vérane, Champ-Garimond), due to their uncompleteness. New divergence timings for salamandrids are estimated based on the new stratigraphic ranges and on the recently recovered phylogenetic position of early salamandrids. Our data strongly support a European origin of salamandrids and biogeographic implications are discussed by combining the current distributions, the fossil record, and the new timing divergence estimates. Our results notably strengthen previous biogeographic hypothesis based on the Cenozoic record, supporting three dispersal events from Europe: the North American Notophthalmus and Taricha clades colonised the Nearctic before the Oligocene through Beringia, whereas the two clades of crocodile newts (Echinotriton and Tylototriton) and the modern Asian newts (e.g. Cynops) likely reached Southeastern Asia during the Oligocene. The regression of the Turgai Sea at the end of the Eocene is herein suggested as the main geographical driver of the dispersal events.
====
====
Free pdf:
Murilo Andrade-Silva & Heitor Francischini (2026)
Reassessing putative lacertoid tracks from the Lower Cretaceous Botucatu Formation (Brazil): ichnotaxonomic ambiguities in an aeolian palaeodesert
Journal of South American Earth Sciences 181: 106154
doi: https://doi.org/10.1016/j.jsames.2026.106154
https://www.sciencedirect.com/science/article/abs/pii/S0895981126002063
Highlights
Reassessment of tetrapod tracks from the Botucatu palaeodesert.
Tracks lack diagnostic features for reliable ichnotaxonomic assignment.
Morphology strongly controlled by substrate and dune slope.
Extramorphological features mimic lacertoid track characteristics.
Aeolian conditions bias track preservation and interpretation.
Integration of taphonomy is essential in desert ichnology.
Abstract
The Lower Cretaceous Botucatu Formation (Paraná Basin, Brazil) preserves one of the largest erg systems in Gondwana, but lacks vertebrate body fossils, making trace fossils the only evidence of its terrestrial fauna. This study presents a reassessment of putative lacertoid tracks using photogrammetry and morphometric analyses. Four specimens were examined to refine their ichnotaxonomic identity and evaluate possible trackmakers. Most tracks are poorly preserved, appearing as shallow, oval depressions without diagnostic features such as digit impressions. Comparisons with lacertoid and crocodylomorph ichnotaxa reveal significant morphological and locomotor inconsistencies, including the absence of key lacertoid traits. Wide variation in pace angulation (68.09°–157.96°) and the presence of marginal expulsion rims indicate strong control by substrate properties and locomotion on dune slopes. These tracks cannot be confidently assigned to any ichnotaxon and are better interpreted as substrate-related artifacts. This study highlights the importance of integrating ichnotaxonomy with sedimentological and taphonomic analyses in desert ichnofaunas.
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