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Evidence for a novel cranial thermoregulatory pathway in thalattosuchian crocodylomorphs Project ID: 000510181 Public
15 Media · 7 Specimens · Creator: Mark Young · Managed by: Mark Young

Evidence for a novel cranial thermoregulatory pathway in thalattosuchian crocodylomorphs. PeerJ. Abstract: Thalattosuchian crocodylomorphs were a diverse clade that lived from the Early Jurassic to the Early Cretaceous. The subclade Metriorhynchoidea underwent a remarkable transition, evolving from semi-aquatic ambush predators into fully aquatic forms living in the open oceans. Thalattosuchians share a peculiar palatal morphology with semi-aquatic and aquatic fossil cetaceans: paired anteroposteriorly aligned grooves along the palatal surface of the bony secondary palate. In extant cetaceans, these grooves are continuous with the greater palatine artery foramina, arteries that supply their oral thermoregulatory structures. Herein, we investigate the origins of thalattosuchian palatal grooves by examining CT scans of six thalattosuchian species (one teleosauroid, two early-diverging metriorhynchoids and three metriorhynchids), and CT scans of eleven extant crocodylian species. All thalattosuchians had paired osseous canals, enclosed by the palatines, that connect the nasal cavity to the oral cavity. These osseous canals open into the oral cavity via foramina at the posterior terminus of the palatal grooves. Extant crocodylians lack both the external grooves and the internal canals. We posit that in thalattosuchians these novel palatal canals transmitted hypertrophied medial nasal vessels (artery and vein), creating a novel heat exchange pathway connecting the palatal vascular plexus to the endocranial region. Given the general hypertrophy of thalattosuchian cephalic vasculature, and their increased blood flow and volume, thalattosuchians would have required a more extensive suite of thermoregulatory pathways to maintain stable temperatures for their neurosensory tissues.

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  ID Part Object Taxonomy Type Date Added Publication Status  
000510291 Segmentation of the palatal canals (internal rostral canals) NHMUK:PAL:PV R 11999 Metriorhynchidae indet. Mesh 2023-03-31 Restricted Download  
000510287 Skull NHMUK:PAL:PV R 11999 Metriorhynchidae indet. Mesh 2023-03-31 Restricted Download  
000510282 Segmentation of the palatal canals (internal rostral canals) mmglv:MM Pa1 Cricosaurus schroederi Mesh 2023-03-31 Restricted Download  
000510274 Skull mmglv:MM Pa1 Cricosaurus schroederi Mesh 2023-03-31 Restricted Download  
000510270 Segmentation of the palatal canals (internal rostral canals) MLP:72-IV-7-1 Cricosaurus araucanensis Mesh 2023-03-31 Restricted Download  
000510266 Skull MLP:72-IV-7-1 Cricosaurus araucanensis Mesh 2023-03-31 Restricted Download  
000510261 Segmentation of the palatal canals (internal rostral canals) nhmuk:pal:PV R 3263 Eoneustes gaudryi Mesh 2023-03-31 Restricted Download  
000510252 Skull nhmuk:pal:PV R 3263 Eoneustes gaudryi Mesh 2023-03-31 Restricted Download  
000510246 Segmentation of the palatal canals (internal rostral canals) NHMUK:PAL:PV OR 32599 Pelagosaurus typus Mesh 2023-03-31 Restricted Download  
000510242 Skull NHMUK:PAL:PV OR 32599 Pelagosaurus typus Mesh 2023-03-31 Restricted Download  
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