A new fossil marine lizard with soft tissues from the Late Cretaceous of southern Italy

Abstract

A new marine lizard showing exceptional soft tissue preservation was found in Late Cretaceous deposits of the Apulian Platform (Puglia, Italy). Primitivus manduriensis gen. et sp. nov. is not only the first evidence of the presence of dolichosaurs in a southern Italian Carbonate Platform, filling a palaeogeographic gap in the Mediterranean Tethys, but also extends the range of this group to the upper Campanian–lower Maastrichtian. Our parsimony analysis recovers a monophyletic non-ophidian pythonomorph clade, including Tetrapodophis amplectus at the stem of Mosasauroidea + Dolichosauridae, which together represent the sister group of Ophidia (modern and fossil snakes). Based on Bayesian inference instead, Pythonomorpha is monophyletic, with Ophidia representing the more deeply nested clade, and the new taxon as basal to all other pythonomorphs. Primitivus displays a fairly conservative morphology in terms of both axial elongation of the trunk and limb reduction, and the coexistence of aquatic adaptations with features hinting at the retention of the ability to move on land suggests a semi-aquatic lifestyle. The exceptional preservation of mineralized muscles, portions of the integument, cartilages and gut content provides unique sources of information about this extinct group of lizards. The new specimen may represent local persistence of a relict dolichosaur population until almost the end of the Cretaceous in the Mediterranean Tethys, and demonstrates the incompleteness of our knowledge of dolichosaur temporal and spatial distributions.

The iliosacral joint in lizards: an osteological and histological analysis

“…In this case, a greatly extended preacetabular process may be a character shared with a terrestrial ancestor. A similar condition is also found in Aigialosaurus dalmaticus (Dutchak & Caldwell, 2006), and aigialosaurs and dolichosaurs are hypothesized to share a common ancestor (Lee & Caldwell, 2000;Caldwell, 2006;Conrad, 2008;Paparella et al 2018). In fact, in obligatory aquatic forms such as mosasauroids, where the ilium, ischium and pubis do not fuse during ontogeny, the preacetabular process is either reduced or completely lost (IP personal observation; Bardet et al 2003;Konishi et al 2012;Mak adi et al 2012;Street & Caldwell, 2017;Jim enez-Huidobro et al 2018).…”

“…Considering that in terrestrial lizards this process becomes indiscernible when the ilium and pubis fuse completely, its relevance in terms of function is arguable, and this variation may be more related to phylogenetic relationships. For example, P. manduriensis is described as a semi‐aquatic lizard in which the fusion of the pelvic bones is never complete during ontogeny (Paparella et al ). In this case, a greatly extended preacetabular process may be a character shared with a terrestrial ancestor.…”

Spatiotemporal Distributions of Non-ophidian Ophidiomorphs, With Implications for Their Origin, Radiation, and Extinction

“…If these remains do represent a coniasaur, it would be the first and only occurrence from Canada. However, Shimada and Ystesund (2007) express their doubt that the specimens represent a dolichosaur, citing personal communications with the original authors. The bonebed also preserves a wide variety of taxa, including chondrichthyans and actinopterygians of several orders, turtles, sauropterygians, and a surprising diversity of birds (Cumbaa et al, 2006).…”

“…The Carlile Shale (which overlies the Greenhorn Formation; Shimada and Bell, 2006) of South Dakota and Kansas has also yielded isolated Coniasaurus remains (Bell and Polcyn, 1996;Shimada and Ystesund, 2007). The Turner Sandy Member of South Dakota (Bell and Polcyn, 1996), and the Fairport Chalk Member of Kansas (Everhart and Darnell, 2004;Shimada and Ystesund, 2007) are the source of the coniasaur material. The Shales were deposited in a very shallow marine environment close to the shoreline and are Upper Turonian in age (biostratigraphy; Hattin, 1982).…”

“…Despite these factors, recent finds have dramatically altered traditional views of the stratigraphic distribution and global range of the dolichosaurs (e.g., Haber and Polcyn, 2005;Hontecillas et al, 2015;Paparella et al, 2018). These new occurrence data indicate that our understanding of the evolution of dolichosaurs needs to be reevaluated.…”