#crocodyliform

Constraints and adaptations in crocodyliform skull evolution

Ananth Srinivas; Jen A. Bright; John A. Cunningham; Sandra Aparecida Simionato Tavares; Fresia Ricardi-Branco; Ismar de Souza Carvalho; Fabiano Vidoi; Emily J. Rayfield

ABSTRACT

Crocodyliforms display a diverse range of skull morphologies through their evolutionary history. Extant crocodilians possess platyrostral (broad and flat) snouts, thought to be sub-optimal for resisting feeding loads due to the conflicting demands of feeding and hydrodynamic constraints. In contrast, numerous Mesozoic crocodyliforms possessed oreinirostral (dome-shaped) skulls, were terrestrial and hence free from hydrodynamic constraint. This study aims to examine the role of function in determining skull shape in crocodyliforms and assesses the difference in stress resistance between oreinirostral and platyrostral taxa. We hypothesize that in the absence of hydrodynamic constraints, oreinirostral taxa have skulls that are better suited for resisting feeding-induced loads. Using finite element analysis, we evaluated biomechanical performance in oreinirostral notosuchian taxa Baurusuchus salgadoensis, Montealtosuchus arrudacamposi  and Caipirasuchus paulistanus, compared to the extant platyrostral Alligator mississippiensis, Crocodylus niloticus and Paleosuchus palpebrosus. Results show that oreinirostral morphologies are comparatively better suited for resisting forces generated during feeding, with increased muscular efficiency, supporting the hypothesis that hydrodynamic constraints influence crocodyliform skull evolution.

Read the paper here:

Tools and materials used: entomological needles of different sizes, ordinary water for softening a very thin layer of rock, and a solution of acetone and b-72 for conservation.

A doting Aegisuchus parent carrying its teeny ‘three-eyed’ babies…

Aegisuchus - “shield crocodile” - an extinct crocodyliform, that may have possibly had an eyespot on its head!

An anonymous request asked for a "large ankylosaur-like herbivorous notosuchian":

Mitafosuchus pachysomatus is descended from Simosuchus-like notosuchians in Madagascar that survived through the K-T extinction.

Highly convergent with the now-extinct ankylosaurs, it's a 5m long (~16'4") squat tank-like herbivore with hoof-like claws, and a wide short snout used for grazing on low vegetation. Heavy interlocking osteoderm amor covers most of its body, protecting it against the big carnivorous crocodyliformes that also still survive in this version of Cenozoic Madagascar.

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Another anon wanted to see a "giant warm blooded lizard":

Atopohippus zestamenus is a descendant of invasive Argentine giant tegu lizards that became established on an island archipelago. At 2m tall (~6'6") and around 6m long (~20') it's an example of island gigantism, and occupies a high-browsing-herbivore ecological niche similar to giant tortoises and prosauropods.

Dinovember, day 21! A group of camptosaurus come down to drink, wary of the other visitors and inhabitants of the water.