Non-crocodylomorph Pseudosuchia osteohistology diversity from Triassic of South America
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Ben Creisler
Apr 17, 2026, 11:08:16 AM (9 days ago) Apr 17
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Ben Creisler
A new paper:
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Denis A. Ponce, Ignacio A. Cerda & Julia B. Desojo (2026)
More diverse than expected: osteohistology of non-crocodylomorph Pseudosuchia from the Triassic of South America
Palaeontology 69(2): e70056
doi: https://doi.org/10.1111/pala.70056
https://onlinelibrary.wiley.com/doi/10.1111/pala.70056
The Pseudosuchia (Diapsida, Archosauria) arose during the Early Triassic and were the dominant large to medium-sized tetrapods in continental ecosystems until the Triassic–Jurassic extinction. Despite this important palaeoecological role, the group remains poorly examined. Here, we report several palaeobiological, palaeoecological and phylogenetic implications based on the bone histology of appendicular elements of seven species of non-crocodylomorph Pseudosuchia from South America, and provide a review of the current state of the osteohistological research on this group. Saurosuchus galilei (Paracrocodylomorpha, Loricata) and Sillosuchus longicervix (Paracrocodylomorpha, Poposauroidea) exhibit fibrolamellar complexes, showing extremely rapid growth. Similarly, Aetobarbakinoides brasiliensis (Aetosauria) and Gracilisuchus stipanicicorum (Gracilisuchidae) display woven-fibred bone, indicative of fast growth. However, Aetosaourides scagliai (Aetosauria) and Tarjadia ruthae (Erpetosuchidae) developed both woven-fibred and parallel fibred bone, which implies an intermediate or moderate growth rate. Finally, Riojasuchus tenuisceps (Ornithosuchidae) records parallel-fibred bone mostly, marking a slower growth rate. Nevertheless, when compared with other pseudosuchians worldwide, this diversity in growth rate does not indicate a reduction in growth rate within the lineage from stem towards crown Pseudosuchia (i.e. a phylogenetic signal). Neither does it correspond with estimated global palaeoclimatic patterns but instead seems to respond to more local environmental influences (e.g. seasonality) and to intrinsic physiological issues. In general, the diversity seen in the growth dynamics of the Triassic non-crocodylomorph Pseudosuchia from South America is similar to that reported for North America and Europe.
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Denis A. Ponce, Ignacio A. Cerda & Julia B. Desojo (2026)
More diverse than expected: osteohistology of non-crocodylomorph Pseudosuchia from the Triassic of South America
Palaeontology 69(2): e70056
doi: https://doi.org/10.1111/pala.70056
https://onlinelibrary.wiley.com/doi/10.1111/pala.70056
The Pseudosuchia (Diapsida, Archosauria) arose during the Early Triassic and were the dominant large to medium-sized tetrapods in continental ecosystems until the Triassic–Jurassic extinction. Despite this important palaeoecological role, the group remains poorly examined. Here, we report several palaeobiological, palaeoecological and phylogenetic implications based on the bone histology of appendicular elements of seven species of non-crocodylomorph Pseudosuchia from South America, and provide a review of the current state of the osteohistological research on this group. Saurosuchus galilei (Paracrocodylomorpha, Loricata) and Sillosuchus longicervix (Paracrocodylomorpha, Poposauroidea) exhibit fibrolamellar complexes, showing extremely rapid growth. Similarly, Aetobarbakinoides brasiliensis (Aetosauria) and Gracilisuchus stipanicicorum (Gracilisuchidae) display woven-fibred bone, indicative of fast growth. However, Aetosaourides scagliai (Aetosauria) and Tarjadia ruthae (Erpetosuchidae) developed both woven-fibred and parallel fibred bone, which implies an intermediate or moderate growth rate. Finally, Riojasuchus tenuisceps (Ornithosuchidae) records parallel-fibred bone mostly, marking a slower growth rate. Nevertheless, when compared with other pseudosuchians worldwide, this diversity in growth rate does not indicate a reduction in growth rate within the lineage from stem towards crown Pseudosuchia (i.e. a phylogenetic signal). Neither does it correspond with estimated global palaeoclimatic patterns but instead seems to respond to more local environmental influences (e.g. seasonality) and to intrinsic physiological issues. In general, the diversity seen in the growth dynamics of the Triassic non-crocodylomorph Pseudosuchia from South America is similar to that reported for North America and Europe.
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