Prehistoric Crocodiles

[Ngala]

The largest thalattosuchian (Crocodylomorpha) supports teleosaurid survival across the Jurassic-Cretaceous boundary
Machimosaurus rex Fanti et al., 2016

*This image is copyright of its original author

Reconstruction credits: Davide Bonadonna.

*This image is copyright of its original author

Fig. 3. Machimosaurus rex type skull, (A) dorsal view, (B) ventral view. Abbreviations: d, dentary; fr, frontal; lj, left jugal; la, lacrimal; mal, maxillary alveoli; mx, maxilla; na, nasal; pa, palatal element; pdb, postdentary bones; posq, postorbital-squamosal bar; rap, retroarticular process; sa, surangular; stfo, fl oor of supratemporal fossa. Scale bar 50 cm.

*This image is copyright of its original author

Fig. 8. Comparison among skulls of Machimosaurus. (A) holotype of M. buffetauti, (B) neotype of M. mosae, © estimated size of the ‘Leira specimen’ of M. hugii, (D) holotype of M. rex. Dashed areas in (A) and (B) indicate size of largest known individuals of those species. (E) Reconstruction of M. rex body based on preserved elements. Figures (A) e © modified from Young et al. (2014b). 

Highlights
• Machimosaurus rex is a new teleosaurid crocodylomorph from Tunisia.
• It is the largest known thalattosuchian, up to 10 m in length.
• M. rex, the first Cretaceous teleosauroid found, was the last-surviving of its group.

Abstract:
"A new teleosaurid from the Lower Cretaceous of Tataouine (Tunisia), Machimosaurus rex sp. nov., definitively falsifies that these crocodylomorphs faced extinction at the end of the Jurassic. Phylogenetic analysis supports its placement closer to M. hugii and M. mosae than M. buffetauti. With the skull length up to 160 cm and an estimated body length of 10 m, M. rex results the largest known thalattosuchian, and the largest known crocodylomorph at its time. This giant thallatosuchian probably was an ambush predator in the lagoonal environments that characterized the Tethyan margin of Africa during the earliest Cretaceous. Whether the Jurassic-Cretaceous mass extinction was real or artefact is debated. The discovery of M. rex supports that the end-Jurassic crisis affected primarily Laurasian biota and its purported magnitude is most likely biased by the incomplete Gondwanan fossil record. The faunal turnovers during the J-K transition are likely interpreted as local extinction events, triggered by regional ecological factors, and survival of widely-distributed and eurytypic forms by means of habitat tracking."

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