The snout of Cricosaurus araucanensis : a case study in novel anatomy of the nasal region of metriorhynchids

Abstract

Metriorhynchids are the only crocodyliforms adapted to pelagic marine life. Snout natural endocasts of the Tithonian (Late Jurassic) metriorhynchid Cricosaurus araucanensis indicated that skeletal changes defining the peculiar metriorhynchid body plan were coupled with changes of the soft cephalic anatomy such as the enlarged salt glands and restructuring of the paranasal sinus system. Seven new natural endocasts of the snout and a 3‐D reconstruction of C. araucanensis are described. Data from these casts and the reconstruction are congruent, and they are combined into an accurate reconstruction that improves our knowledge of the pre‐orbital anatomy. The olfactory tract, bulbs, olfactory nasal region and the anterior extension of the antorbital sinus within the maxilla are recognized. Osteological correlates of the salt gland body are also proposed. Palaeobiological inferences are erected based on the integration of natural endocasts and 3‐D reconstruction data. It is proposed that C. araucanensis nasal salt glands were highly vascularized with a blood supply comparable with those of extant marine birds. Reduced olfactory bulbs and olfactory nasal region indicate that the aerial olfaction, differing from extant crocodilians, was not well developed.

Sensory Evolution and Ecology of Early Turtles Revealed by Digital Endocranial Reconstructions

“…Outlines were smoothed ten times to eliminate pixel noise, and 23 Fourier harmonics were found to describe the outlines of all sampled taxa sufficiently (average Fourier power > 99%) (see also Supplementary Material). In addition to the reconstructed endocasts, further outlines of 52 taxa were collected from the literature (Hopson, 1979;Franzosa, 2004;Neenan and Scheyer, 2012;Bona and Paulina-Carabajal, 2013;Carabajal et al, 2013;George and Holliday, 2013;Herrera et al, 2013;Holloway et al, 2013;Lautenschlager and Butler, 2016;von Baczko and Desojo, 2016;Jirak and Janacek, 2017;Laaß et al, 2017;Paulina-Carabajal et al, 2017;Pierce et al, 2017; Digimorph 1 ) for different turtle, archosauromorph, lepidosauromorph and other amniote taxa (for list of taxa see Table S1). These outlines were redrawn in Adobe Illustrator to ensure sufficient resolution for the digitization process.…”

Metriorhynchidae (Crocodylomorpha: Thalattosuchia) From Upper Jurassic–lower Cretaceous of Neuquén Basin (Argentina), With Comments on the Natural Casts of the Brain

“…paddle-like forelimbs, hypocercal tail, osteoporotic-like bone tissue, loss of osteoderms (e.g., Fraas, 1902; Andrews, 1913; Hua and Buffrénil, 1996;Young et al, 2010), and enlarged external carotid foramen and canal, enlarged and highly vascularised nasal salt gland, preorbital fenestra related with the drainage of salt gland, and reduced olfactory tract and bulbs Gasparini, 2000, 2008;Fernández and Herrera, 2009;Pol and Gasparini, 2009;Fernández et al, 2011;Herrera et al, 2013a;Herrera and Vennari, 2015). Metriorhynchidae is a Middle Jurassic to Early Cretaceous group that mainly lived in the Tethys and Pacific oceans.…”

“…In the late 90s, the finding of some natural casts of the nasal salt gland of Cricosaurus araucanensis in the collection of the División Paleontología Vertebrados (Museo de La Plata) was the base of a series of works in which paleobiological aspects of Patagonian metriorhynchid began to be analyzed. Gasparini (2000, 2008), Herrera et al (2013a) described the natural casts of the preorbital region (i.e., nasal gland, paranasal sinus system and related structures) of the skull.…”

Reptiles Extintos - Volumen en Homenaje a Zulma Gasparini

“…La comprensión de estos cambios permitirá delimitar las innovaciones evolutivas claves que le permitieron a los metriorrínquidos la conquista, sin paralelo entre los arcosaurios, del medio pelágico. Fernández, 2005, 2011 1913; Hua and Buffrénil, 1996;Young et al, 2010), and enlarged external carotid foramen and canal, enlarged and highly vascularised nasal salt gland, preorbital fenestra related with the drainage of salt gland, and reduced olfactory tract and bulbs Gasparini, 2000, 2008;Fernández and Herrera, 2009;Pol and Gasparini, 2009;Fernández et al, 2011;Herrera et al, 2013a;Herrera and Vennari, 2015). Metriorhynchidae is a Middle Jurassic to…”