Evidence of thalattosuchian crocodylomorphs in the Portland Stone Formation (Late Jurassic) of England, and a discussion on Cretaceous teleosauroids

Young, Mark T.; Sachs, Sven

doi:10.1080/08912963.2019.1709453

Cited by 5 publications

(2 citation statements)

References 29 publications

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“…Thus, changes to the vestibular system apparently did not lead the transition, but likely were a response to changing sensory requirements as metriorhynchids moved into deeper, more open waters. Furthermore, after the transition occurred, semiaquatic teleosauroids persisted alongside pelagic metriorhynchids for tens of millions of years (32).…”

Section: Discussionmentioning

confidence: 99%

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

Schwab

Young

Neenan

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Major evolutionary transitions, in which animals develop new body plans and adapt to dramatically new habitats and lifestyles, have punctuated the history of life. The origin of cetaceans from land-living mammals is among the most famous of these events. Much earlier, during the Mesozoic Era, many reptile groups also moved from land to water, but these transitions are more poorly understood. We use computed tomography to study changes in the inner ear vestibular system, involved in sensing balance and equilibrium, as one of these groups, extinct crocodile relatives called thalattosuchians, transitioned from terrestrial ancestors into pelagic (open ocean) swimmers. We find that the morphology of the vestibular system corresponds to habitat, with pelagic thalattosuchians exhibiting a more compact labyrinth with wider semicircular canal diameters and an enlarged vestibule, reminiscent of modified and miniaturized labyrinths of other marine reptiles and cetaceans. Pelagic thalattosuchians with modified inner ears were the culmination of an evolutionary trend with a long semiaquatic phase, and their pelagic vestibular systems appeared after the first changes to the postcranial skeleton that enhanced their ability to swim. This is strikingly different from cetaceans, which miniaturized their labyrinths soon after entering the water, without a prolonged semiaquatic stage. Thus, thalattosuchians and cetaceans became secondarily aquatic in different ways and at different paces, showing that there are different routes for the same type of transition.

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Section: Discussionmentioning

confidence: 99%

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

Schwab

Young

Neenan

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…This metric matches or exceeds the precision for the most commonly used linear measure of snout-vent length for assessing size. It is, thus, quantitatively comparable to other approaches for estimating body mass in crocodyliforms, but it utilizes a linear dimension that is more commonly preserved in fossil specimens (O'Brien et al, 2019;Scheyer et al, 2019;Young & Sachs, 2020).…”

Section: Empirically Derived Performance Proxiesmentioning

confidence: 95%

Unexpected bite‐force conservatism as a stable performance foundation across mesoeucrocodylian historical diversity

Gignac

Smaers

O’Brien

2021

The Anatomical Record

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Effective interpretation of historical selective regimes requires comprehensive in vivo performance evaluations and well‐constrained ecomorphological proxies. The feeding apparatus is a frequent target of such evolutionary studies due to a direct relationship between feeding and survivorship, and the durability of craniodental elements in the fossil record. Among vertebrates, behaviors such as bite force have been central to evaluation of clade dynamics; yet, in the absence of detailed performance studies, such evaluations can misidentify potential selective factors and their roles. Here, we combine the results of a total‐clade performance study with fossil‐inclusive, phylogenetically informed methods to assess bite‐force proxies throughout mesoeucrocodylian evolution. Although bite‐force shifts were previously thought to respond to changing rostrodental selective regimes, we find body‐size dependent conservation of performance proxies throughout the history of the clade, indicating stabilizing selection for bite‐force potential. Such stasis reveals that mesoeucrocodylians with dietary ecologies as disparate as herbivory and hypercarnivory maintain similar bite‐force‐to‐body‐size relationships, a pattern which contrasts the precept that vertebrate bite forces should vary most strongly by diet. Furthermore, it may signal that bite‐force conservation supported mesoeucrocodylian craniodental disparity by providing a stable performance foundation for the exploration of novel ecomorphospace.

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On the validity of the British Upper Jurassic turtle “Pleurosternon portlandicum” (Paracryptodira, Pleurosternidae)

Guerrero

Pérez‐García

2020

J Iber Geol

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Evidence of thalattosuchian crocodylomorphs in the Portland Stone Formation (Late Jurassic) of England, and a discussion on Cretaceous teleosauroids

Cited by 5 publications

References 29 publications

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

Unexpected bite‐force conservatism as a stable performance foundation across mesoeucrocodylian historical diversity

On the validity of the British Upper Jurassic turtle “Pleurosternon portlandicum” (Paracryptodira, Pleurosternidae)

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