The non-archosauriform archosauromorph Dinocephalosaurus orientalis was first described from the Upper Member of the Guanling Formation (late Anisian, Middle Triassic) of Guizhou Province by Li in 2003 on the basis of a complete articulated skull and the first three cervical vertebrae exposed in dorsal to right lateral view. Since then, additional specimens have been discovered in southwestern China. Here, five newly discovered specimens are described for the first time, and redescriptions of the holotype IVPP V13767 and another referred specimen, IVPP V13898, are provided. Together, these permit the description of the complete skeleton of this remarkable long-necked marine reptile. The postcranial skeleton is as much as 6 metres long, and characterised by its long tail and even longer neck. The appendicular skeleton exhibits a high degree of skeletal paedomorphosis recalling that of many sauropterygians, but the skull and neck are completely inconsistent with sauropterygian affinities. The palate does not extend back over the basisphenoid region and lacks any development of the closed condition typical of sauropterygians. The arrangement of cranial elements, including the presence of narial fossae, is very similar to that seen in another long-necked archosauromorph, Tanystropheus hydroides, which at least in part represents a convergence related to an aquatic piscivorous lifestyle. The long and low cervical vertebrae support exceptionally elongate cervical ribs that extend across multiple intervertebral joints and contribute to a ‘stiffening bundle of ribs’ extending along the entire ventral side of the neck, as in many other non-crocopodan archosauromorphs. The functional significance of the extraordinarily elongate neck is hard to discern but it presumably played a key role in feeding, and it is probably analogous to the elongate necks seen in pelagic, long-necked plesiosaurs. Dinocephalosaurus orientalis was almost certainly a fully marine reptile and even gave birth at sea.

The Middle and early Late Triassic of southern China is well known for a remarkable diversity of marine vertebrates, particularly reptiles, including an abundance of intriguing new forms (e.g., Jiang et al., 2005; Hu et al., 2011; Li et al., 2016). Here we describe a new diapsid from Yunnan Province. It possesses an elongate neck that exhibits a remarkable similarity to that of many Protorosauria, yet in other respects the skull and postcranium are much less derived.

The new taxon is part of the so-called Panxian-Luoping Fauna and the deposits correspond to the Upper Member of the Guanling Formation, comprising thin to medium bedded, gray to dark-gray laminated marly limestone and limestone, with several layers of bentonite intercalated in the fossil level at Panxian (Wan, 2002; Motani et al., 2008; Jiang et al., 2009). Their age is Pelsonian (middle Anisian, Middle Triassic) as is indicated by the conodont Nicoraella kockeli Zone (Sun et al., 2006; Zhang et al., 2009). A recent U-Pb study indicates the absolute age of these middle Anisian beds to be close to 244 Ma (Wang et al., 2014).

The fossil snake species Haasiophis terrasanctus Tchernov, Rieppel, Zaher, Polcyn, and Jacobs, 2000, from the early Upper Cretaceous of the Middle East, is described and illustrated, following a review of the current debate on snake relationships and origins. The description and discussion presented here adds important detail to the knowledge of this taxon and its phylogenetic significance beyond the limited account presented in the original description of Haasiophis. The species is remarkable in that it shows the skull of a relatively advanced (i.e., macrostomatan) snake, yet preserves well-developed hind limbs. The hind limb includes a femur, tibia, fibula, astragalus, calcaneum, distal tarsal four, and remains of four metatarsals and two phalanges. Haasiophis cannot be considered a juvenile specimen of Pachyrhachis. The implications of the presence of well-developed hind limbs in Haasiophis, Pachyrhachis, and Podophis for the cladistic analysis of the phylogenetic interrelationships of these fossil snakes is discussed. The presence of well-developed hind limbs in Pachyrhachis and Haasiophis also creates methodological problems for the cladistic analysis of the phylogenetic relationships of these fossil snakes. Scenarios of snake origins are reviewed and found to be deficient in the absence of a well-corroborated hypothesis of snake relationships within Squamata.

The marine Triassic rocks of Nevada are well known for their ichthyosaur finds, and a number of new genera and species were described from this state. Based on a few vertebrae, Leidy (1868) erected a new Middle Triassic ichthyosaur genus, Cymbospondylys, with two species, C. petrinus and C. piscosus. The type material of C. petrinus came from the Prida Formation of the southern Humboldt Range, and that of C. piscosus from the Favret Formation of the New Pass Range.

In this paper we analyze the ontogenies of four species of pachypleurosaur (Reptilia: Sauropterygia) occurring in Triassic-age deposits in the Monte San Giorgio region, Switzerland. Preservation of multiple complete specimens representing a growth series from each taxon allows the comparison of ontogenetic trajectories through a space composed of nine variables important in the evolution of the clade. Trajectories are characterized using the multivariate generalization of the allometry equation and then compared through calculations of the angles between allometry vectors. Individual coefficients of vectors are compared after calculation of bootstrapped confidence intervals. Pachypleurosaur ontogeny is found to be allometric and generally conserved, although significant differences between taxa exist. Shape-disassociated allometric changes characterize the transition between Serpianosaurus and Neusticosaurus, while allometric changes within Neusticosaurus are less significant. N. edwardsii is inferred to have arisen through hypermorphosis. Interpretation of whole-body heterochrony in multivariate analysis is discussed.

A pleurodontan iguanian from the Green River Formation (Eocene) is described in detail and named. The new taxon is known only from a single specimen preserving all areas of the body. Although many of the bone surfaces are eroded, almost all of the skeleton is present and some cartilaginous elements are preserved. The new taxon shares important characteristics with the extant anisolepines and leiosaurines, including the morphology and placement of the caudal autotomy planes, the postxiphisternal inscriptional ribs, and notched or fenestrated clavicles that are expanded proximally. This is the earliest complete iguanian known from the Americas and the earliest known iguanian that may be confidently referred to an extant “family.” A phylogenetic analysis including this taxon and other fossil and extant iguanians offers some support for the monophyly of Polychrotidae sensu lato, Tropiduridae sensu lato, and non-acrodont iguanians (Pleurodonta).

The skeleton of a newly discovered, exceptionally preserved specimen of Saniwa ensidens is described in detail. the fossil consists of a complete articulated skeleton exposed in dorsal view. It adds important additional information to our knowledge of the anatomy of this fossil varanoid taxon, including a detailed description of the dermatocranium in dorsal view, complete vertebral counts, and a detailed account of the appendicular skeleton. Cartilage preservation allows the identification of treacheal rings, sternum, inscriptional ribs, epicoracoid and suprascapula. Patches of skin are preserved on dermal skull bones, and scattered scales surround the entire skeleton. Incomplete ossification of carpal and tarsal elements, as well as of epiphyses, indicate that the specimen is not fully mature.

Eosaniwa koehni is an enigmatic platynotan that differs from related varanoids in the possession of a very long snout resulting in extremely elongate nasals and vomers; a robust and broad jugal; the presence of denticles on palatines, pterygoids, and vomers; the presence of a subdental shelf on the dentary; and a strongly twisted retroarticular process on the mandible. Phylogenetic analysis suggests that Eosaniwa is a derived varanoid platynotan, nested within a clade also including mosasauroids, Coniasaurus, and Paravaranus.

A new species of the genus Nothosaurus from the Lower Muschelkalk of Winterswijk, The Netherlands, shows relatively plesiomorphic features such as a relatively forward position of the pineal foramen. The jugal enters into the ventral margin of the orbit, which would also be regarded as plesiomorphic, were it not that this feature optimizes unequivocally as a reversal and, hence, as a diagnostic (derived) character of the new taxon. The new taxon does not, however, increase the fit of the cladogram for the phylogenetic relationships within Nothosaurus to the stratigraphic record of the genus. The basal position of Nothosaurus juvenilis remains problematic.

The Hapsidopareiontidae are microsaurian amphibians known only from the Lower Permian of the U.S. The hapsidopareiontid skull has a large temporal embayment that occupies most of the area of the cheek, in which the quadratojugal is either absent (Hapsidopareion) or present and greatly reduced (Llistrofus). the unique holotype skull of Llistrofus pricei is well preserved in soft clay. It was originally prepared and described in dorsal view only, but has now been prepared completely free of the matrix. This permitted the first description of the palate, occiput and mandible along with a redescription of the rest of the skull, resulting in substantial emendation of previously published descriptions. Comparison with the eight known complete and partial skulls of Hapsidopareion lepton demonstrates that the two genera are much more similar than had been recognized earlier. Their continued separation is advocated, however, based on size difference, a small number of osteological differences, and the difficulty of obtaining comparably detailed morphological information for Hapsidopareion, which is less well preserved than the Llistrofus specimen. the new morphological information, combined with results of recently published cladistic analyses, suggests that Hapsidopareion and Llistrofus are the only microsaurs that can at present be assigned to the Hapsidopareiontidae. the large temporal embayment of hapsidopareiontids might be thought to have significant functional implications, possibly including “escape” of jaw adductor musculature onto the skull roof. Detailed consideration of this possibility reveals morphological evidence to the contrary, however, and the functional implications of the embayment remain uncertain.

Largocephalosaurus polycarpon Cheng et al. 2012a was erected after the study of the skull and some parts of a skeleton and considered to be an eosauropterygian. Here we describe a new species of the genus, Largocephalosaurus qianensis, based on three specimens. The new species provides many anatomical details which were described only briefly or not at all in the type species, and clearly indicates that Largocephalosaurus is a saurosphargid. It differs from the type species mainly in having three premaxillary teeth, a very short retroarticular process, a large pineal foramen, two sacral vertebrae, and elongated small granular osteoderms mixed with some large ones along the lateral most side of the body. With additional information from the new species, we revise the diagnosis and the phylogenetic relationships of Largocephalosaurus and clarify a set of diagnostic features for the Saurosphargidae Li et al. 2011. Largocephalosaurus is characterized primarily by an oval supratemporal fenestra, an elongate dorsal ‘rib-basket’, a narrow and elongate transverse process of the dorsal vertebrae, and the lack of a complete dorsal carapace of osteoderms. The Saurosphargidae is distinct mainly in having a retracted external naris, a jugal–squamosal contact, a large supratemporal extensively contacting the quadrate shaft, a leaf-like tooth crown with convex labial surface and concave lingual surface, a closed dorsal ‘rib-basket’, many dorsal osteoderms, a large boomerang-like or atypical T-shaped interclavicle. Current evidence suggests that the Saurosphargidae is the sister-group of the Sauropterygia and that Largocephalosaurus is the sister-group of the Saurosphargis–Sinosaurosphargis clade within the family.

The architects of the modern synthesis banned essentialism from evolutionary theory. This rejection of essentialism was motivated by Darwin's theory of natural selection, and the continuity of evolutionary transformation. Contemporary evolutionary biology witnesses a renaissance of essentialism in three contexts: “origin essentialism” with respect to species and supraspecific taxa, the bar coding of species on the basis of discontinuities of DNA variation between populations, and the search for laws of evolutionary developmental biology. Such “new essentialism” in contemporary biology must be of a new kind that accommodates relational (extrinsic) properties as historical essences and cluster concepts of natural kinds.

The skull anatomy of uropeltines is reviewed, and new data is presented on the highly derived otico-occipital region. A phylogenetic analysis of uropeltine interrelationships using parsimony is performed using characters derived from skull structure. The basal position of the genus Melanophidium is confirmed; Pseudotyphlops is a relatively derived uropeltine, in spite of its relatively large size. The monophyly of the genera Melanophidium and Rhinophis requires further testing.