Ben Creisler
New papers:
Opisuchus meieri gen. et sp. nov.Â
Thalattosuchia, a clade of Mesozoic aquatic crocodyliforms, were the only archosaurs that ever became fully adapted to marine ecosystems. They are represented by two clades, the semiaquatic teleosauroids and the metriorhynchoids, which include fully pelagic forms. So far, little is known on the early evolutionary history of Metriorhynchoidea and data are sparse, especially from the early Middle Jurassic. Opisuchus meieri gen. et sp. nov. a metriorhynchoid crocodyliform from the early Aalenian (early Middle Jurassic) of southern Germany, is described here. It is one of the most complete specimens of a non-metriorhynchid metriorhynchoid, and the best-preserved thalattosuchian described from the Aalenian. The new taxon is represented by a nearly complete skull, which has a unique combination of characters distinguishing it from other species of Metriorhynchoidea. It displays a mosaic of plesiomorphic and apomorphic morphological features that sheds new light on early metriorhynchoid evolution. This taxon is an important puzzle piece, which will help to better track the mosaic character distribution in Thalattosuchia.
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(no abstract, from the text...)
Pilgrim (1908, 1912) was the first to describe and name several crocodylian species from the Bugti Hills, including a number of longirostrine forms (Martin, 2018). With these remains, Pilgrim (1908) erected Crocodilus bugtiensis, which was later described (Pilgrim, 1912) and represented by a portion of the rostrum (IM E221) from Pishi Nala near Dera Bugti. Although no overlapping material exists to relate the skull material described by Pilgrim (1912) with the mandibular material described above, we consider all these specimens to represent a single species...
The estimated size of adult A. bugtiensis falls in the range of other large fossil Crocodylus (Brochu and Storrs, 2012; Delfino and De Vos, 2014). The fossil record offers repeated instances of gigantism among semiaquatic crocodylomorphs (Table 2), and based on cranial material, the largest exemplars could be estimated to surpass a TBL of 10 m (Head, 2001; Sereno et al., 2001; Aguilera et al., 2006; Riff and Aguilera, 2008). Astorgosuchus bugtiensis was retrieved in the same fluviolacustrine deposits as the large tomistomines 'Gavialis' curvirostris and 'Gavialis' breviceps (Pilgrim, 1908, 1912; Martin, 2018). Both âGavialisâ taxa cooccur with several megaherbivores, such as rhinocerotoids and chalicotheriids among perissodactyls, anthracotheriid artiodactyls, and proboscideans (Antoine et al., 2003, 2004, 2013; MÃtais et al., 2009a; Lihoreau et al., 2017).