Morphology of the skull of the white‐nosed blindsnake, Liotyphlops albirostris (Scolecophidia: Anomalepididae)

Abstract

This article presents a detailed description and illustration of the skull of Liotyphlops albirostris in comparison to the skulls of Typhlophis squamosus, Leptotyphlops dulcis, and Typhlops jamaicensis, based on high-resolution X-ray computed tomography (HRXCT). The skull of T. squamosus is illustrated and discussed in detail for the first time. A number of uniquely shared derived characters is identified that support the monophyly of the clade Anomalepididae. Anomalepidids retain some features that are plesiomorphic relative to other scolecophidians, such as the presence of a supratemporal (except in Anomalepis) and ectopterygoid. The homology of the element located posteroventral to the eyeball in anomalepidids and variably referred to as a jugal or postorbital (or a fusion of both in Anomalepis) remains unknown. Scolecophidians exhibit a highly derived skull morphology adapted to head-first burrowing. Both anomalepidids and typhlopids evolved a condition known as an "outer shell design," but did so in different ways. Leptotyphlopids combine elements of both the anomalepidid and typhlopid snout morphologies.

Embryology of the VNO and associated structures in the grass snake Natrix natrix (Squamata: Natricinae): a 3D perspective

“…Moreover, the choanal groove in adults geckoes is not vestigial [24]. *** In some species of Scolecophidia the vomeronasal nerve enters the organ through a vertical foramen in the septomaxilla [42, 43]. Silhouettes in the legend (except Henophidia) from http://phylopic.org/.…”

“…This resembles the condition characteristic of the more basal snakes, Henophidia, which are characterized by one, two or rarely three openings for the vomeronasal nerve [32, 34]. Interestingly, in scolecophidians which are the most basal extant snakes, the connection of the vomeronasal nerve with the VNO is restricted to the posterior gap between the vomer and septomaxilla (condition similar to this occurring in lizard-like autarchoglossans), or the vomeronasal nerve enters the organ through a vertical foramen in the septomaxilla [42, 43, 72, 80]. …”

Primary homologies of the circumorbital bones of snakes

“…Skulls of anomalepidid snakes. ( A ), Liotyphlops albirostris , lateral view (drawing based on Rieppel et al, ); ( B ), Typhlophis scutatus , lateral view (drawing based on Rieppel et al, ); ( C ), Anomalepis flavapices , lateral view (AMNH R‐6966). POE is highlighted in red, blue circle indicates the position of the eye.…”

Unusual cranial and postcranial anatomy in the archetypal ankylosaur Ankylosaurus magniventris

“…Extant mammals that engage in rooting or grubbing for food, such as suids, aardvarks, and armadillos, tend to have long snouts tipped by a flat disc with forward-facing nostrils, which is unlike the morphology observed in Ankylosaurus. However, ventrally placed or dorsally roofed external nares, combined with a solid, blunt, shovel-like rostrum, are present in several fossorial squamates of the clades Amphisbaenia and Scolecophidia (e.g., Diplometopon zarudnyi, Liotyphlops albirostris, Rhineura floridana, Typhlops jamaicensis; Maisano et al 2006;Rieppel et al 2009;Gauthier et al 2012). While we do not suggest that Ankylosaurus was fossorial, it is possible that the similarities in rostral anatomy between this ankylosaur, amphisbaenians, and scolecophidians may reflect convergent adaptations for earth moving behaviours.…”