We present a time-scaled analysis based on morphological characters to estimate the divergence ages for the major batoid clades. Two approaches were used: tip-dating, which allows the extinct taxa to be included as terminals, assessing the phylogenetic relations and their divergence time simultaneously; and basic and minimum branch length (‘a posteriori' methods) that date a pre-existing unscaled topology, given a set of stratigraphic data for the taxa involved. We used stratigraphic indexes to compare the divergence ages recovered by both methods. The tip-dating approach obtained a more resolved topology and slightly better stratigraphic index scores than the other methods. Overall the tip-dating analysis recovered slightly earlier divergence ages than the rest of the time dating analyses and the known fossil record of the groups. However, these divergence ages were not as old as those estimated by molecular analysis. Our results suggest the diversity increase through the Late Jurassic–Early Cretaceous might not be gradual, and that Early Cretaceous diversity could be significantly higher. As several divergence events are placed in the Early Cretaceous, there is a suggestion that an active period of cladogenesis leads to the Late Cretaceous high diversity. The last divergence events recovered by the present analysis occurred in the Paleogene and led to the extant groups of batoids.

The Birket Qarun Formation, sampling upper Eocene deposits of the Fayum Depression, has been the subject of disagreement in terms of the environmental deposition. The formation has traditionally been considered to be a marine deposit but, more recently, one particular site, Birket Qarun Locality 2 (BQ-2), has been reported to have freshwater vertebrates, indicating that at least this locality in the formation contains terrestrial deposits. We here report a new varied assemblage of fossil catfishes from BQ-2, which adds new information with which to interpret the paleoenvironment of the locality. The new BQ-2 catfish assemblage includes the earliest record of the freshwater family Bagridae in Africa, as well as the oldest records of Fajumia and Socnopaea, otherwise known only from the overlying marine deposits of the Qasr el-Sagha Formation. Notable among the finds are remains of Arius fraasi and two additional species of marine ariid catfishes, representing the first such occurrences from the Fayum deposits. These occurrences indicate that BQ-2 likely had marine influences, or perhaps that Fajumia, Socnopaea, and Arius were euryhaline. In addition, the freshwater families Claroteidae and Mochokidae are represented among our collection. The new material documents the presence of a variety of taxa, and in addition it documents the variation in body size of members of the same family. Most evidence from other vertebrate fossils indicates that BQ-2 is a freshwater deposit, but some elements of the new catfish collection suggest the presence of nearshore marine influences, indicating that a much more complex environment was present.

Lungfish tooth plates have been known from Cretaceous deposits at Lightning Ridge and nearby opal fields since 1914. These specimens are reasonably complete, and assigned to a common Mesozoic genus, Metaceratodus wollastoni. Later, several small fragments of lungfish tooth plates collected in 1981 were described as indistinguishable from tooth plates of the living Australian lungfish, Neoceratodus forsteri. However, new dental material has since been collected, consisting of tooth plates with attached bone from both jaws, and this has prompted a revision of the original determination. A new species of lungfish, Neoceratodus potkooroki, can be erected, based on characters of both the tooth plates and the jaw bones, and N. forsteri can no longer be considered a Cretaceous taxon. The oldest occurrence of N. forsteri is now considered to be Pliocene, in the Chinchilla Sands from Chinchilla in Queensland. Material of two other species of dipnoan, M. wollastoni and Ceratodus diutinus, have since been collected from the Cretaceous Griman Creek Formation, and both are easily distinguished from the new species of Neoceratodus.

We describe a new fossil species of Ceratophrys from cave sediments in Brazil tentatively assessed as late Pleistocene–early Holocene in age. The specimen consists of a nearly complete skull that is missing only the right premaxilla and the right columella. A detailed description and comparative analysis, which considers both living and fossil species, supports the conclusion that the specimen represents a previously unknown, extinct species of Ceratophrys. Poorly represented and assessed characters, paleodistribution of Ceratophryidae, and the taxonomic rectification of the Ceratophrys fossil specimens described by Günther (1859) are also discussed.

The Rhizodontida are a group of tetrapodomorph sarcopterygian fishes with a worldwide distribution in the Devonian and Carboniferous periods. Rhizodontids were first described in the U.K., with Carboniferous taxa such as Rhizodus, Strepsodus, and Archichthys each based on isolated teeth (probably symphysial tusks) with distinctive morphologies. Some isolated fin material has also been described, including humeri, but this material has generally been assigned to either Rhizodus or Strepsodus purely on the basis of its size (with the larger material assigned to Rhizodus) or lithology (with specimens in coalshale assigned to Strepsodus). As a first step towards resolving this situation, we have utilized micro-CT scans of U.K. rhizodontid humeri, including newly discovered specimens from Scotland, to establish four distinct humeral morphogroups. This provides a robust framework for interpreting future discoveries, with the hope that these morphogroups can ultimately be securely linked with the distinctive tooth morphologies. The histology of the endochondral bone of the rhizodontid humerus is also described for the first time.

The fossil record of early diapsids is sparse, specimens are uncommon and often incomplete, and phylogenetic relationships are hard to determine. A new taxon of early diapsid, Feralisaurus corami from the Middle Triassic of Devon, south-western England, is here named and described from an incomplete but mostly articulated skeleton, comprising skull, vertebrae, pectoral girdle, ribs, and the right forelimb. CT scanning and the resultant 3D model of the skeleton reveal anatomical details otherwise buried in the sandstone matrix. This new diapsid is characterized by a plesiomorphically high maxilla without a prominent nasal process, a quadrate with a lateral conch, a low jugal with small posterior process, conical teeth with pleurodont implantation, a high coronoid process, notochordal vertebrae, a long humerus with an entepicondylar foramen, rod-like clavicles, a ‘T'-shaped interclavicle, and a ventrolateral process of the scapulocoracoid. Phylogenetic analyses, although showing generalized weak support, retrieved Feralisaurus within Neodiapsida or stem-group Lepidosauromorpha: its morphology supports the latter hypothesis. This specimen adds to our knowledge of the early diversification of Lepidosauromorpha and of English Middle Triassic terrestrial faunas.

Brevicaudosaurus jiyangshanensis, gen. et sp. nov., a new nothosauroid, is established on the basis of two nearly complete skeletons from the Middle Triassic (Ladinian) of China. Its skull is diagnostic in having a wide and constricted snout, a large supratemporal fossa slightly larger than the orbit, and a parietal table strongly constricted posteriorly. Postcranial specializations include a short trunk with 14 dorsal vertebrae, a short tail shorter than the skull-neck region in length, a stout anterolateral process on the clavicle, an extremely massive and broadened mid-diaphysis of the humerus, a strongly expanded proximal head of the ulna, seven ossified carpals, and a phalangeal reduction in the pes. In addition, the strongly pachyostotic postcranial skeleton may indicate a slow mode of swimming underwater and a benthic carnivorous feeding habit for B. jiyangshanensis. Phylogenetically, it is the sister taxon of the Nothosaurus-Lariosaurus clade within Nothosauroidea. The discovery of this new nothosauroid not only contributes to local faunal diversity and expands the known range of sauropterygian life styles during the late Middle Triassic, but also provides a chance to test the phylogenetic relationships of the Eosauropterygia hypothesized by previous studies.

Prognathodon stadtmani was discovered in the Campanian portion of the Upper Cretaceous Mancos Shale in western Colorado in 1975. Following its original description almost two decades ago, more material of the holotype was prepared. Those new elements include a quadrate, often considered one of the most critical bones for understanding mosasaur systematics, portions of the skull roof, posterior mandible, and braincase. Prognathodon stadtmani exhibits a suite of features that include both derived character states observed in later mosasaurines and primitive features present in earlier members of the clade, such as Clidastes. Although the quadrate resembles those of Prognathodon and Globidens in some respects, it lacks fusion between the suprastapedial process and ascending tympanic rim observed in those taxa. I ran a series of phylogenetic analyses using parsimony and Bayesian inference to understand the relationships of this taxon. Regardless of character selection or methodology, ‘Prognathodon’ stadtmani was not found to be monophyletic with the rest of the genus Prognathodon. Depending on method, it was recovered as the sister taxon to the rest of Globidensini, the sister taxon to Mosasaurini + Globidens, or an early diverging mosasaurine outside of both Globidensini and Mosasaurini. Owing to these results, I assign the type to a new genus, Gnathomortis, gen. nov., yielding the species Gnathomortis stadtmani, comb. nov. Furthermore, the rest of the genus Prognathodon and the clade Globidensini more broadly were not consistently recovered as monophyletic. Many characters of the quadrate and the dentition that typically united those clades are optimized as homoplastic based on my resulting topologies.

The titanosaurian sauropod dinosaur Savannasaurus elliottorum is represented by a partial postcranial skeleton from the lower Upper Cretaceous (Cenomanian–lowermost Turonian) Winton Formation of Queensland, northeast Australia. Here, we present a detailed description of this specimen, as well as an emended diagnosis for this titanosaur. Savannasaurus elliottorum displays numerous character states that are generally regarded as plesiomorphic for Titanosauria, as well as several traits that are often regarded as apomorphic of that clade or a less inclusive subset thereof. Several features of Savannasaurus support a close relationship with the coeval Diamantinasaurus matildae, and this clade appears to occupy an early-branching position within Titanosauria. Relative to body size, the thoracic and abdominal breadth of Savannasaurus is greater than that seen in giant titanosaurs such as the contemporaneous South American lognkosaurians; however, this relative breadth is not quite as extreme as that of the small-bodied latest Cretaceous saltasaurines, or Opisthocoelicaudia skarzynskii. The possible advantages engendered by the barrel-shaped thorax, robust limbs, wide-gauge gait, and lack of hyposphene-hypantrum articulations are explored, and it is hypothesized that these traits were positively selected by the wet, temperate floodplain environment in which Savannasaurus lived. Greater stability and flexibility might have reduced the risk of bogging, and/or facilitated more expedient self-extraction from muddy waterholes. Similar environmental pressures acting upon other titanosaurian taxa or clades elsewhere might have led to the repeated independent development, or accentuation, of the bauplan regarded as ‘typical’ for the clade Titanosauria. This would explain the many observed convergences between Savannasaurus and Diamantinasaurus, and Saltasauridae.

Starting with his first report on fossil footprints from the Connecticut Valley over 180 years ago, Edward Hitchcock described what he interpreted as a burgeoning ancient fauna founded on ever-increasing nominal track diversity. For three decades, Hitchcock made countless contributions to ichnology, but his inference of thin-toed animals (Leptodactyli) from thin-toed tracks is flawed by modern criteria. Leptodactylous tracks are now recognized as variants made by thick-toed feet penetrating into soft, collapsing substrates. Herein, we take a closer look at the creation of such penetrative tracks using computer simulations of particle flow. Classic specimens are used to demonstrate how different modes of surface presentation make penetrative tracks challenging to recognize and interpret. Evaluation of 266 specimens from 43 leptodactylous ichnotaxa reveals that ∼90% are penetrative. We propose that a reliance on a single formation mechanism confounded Hitchcock's ability to reliably recognize different trackmakers. This is not an old problem applicable only to fossils collected long ago; domination of a transmission-based model continues to bias the field today. Most texts and many publications either omit collapsed penetrative tracks or fail to recognize them as a significant source of variation. Without proper regard for subsurface toe movement and sediment flow, inferences of foot shape from track shape can, as for Hitchcock, be led far astray. The misidentification and misunderstanding of penetrative tracks impact our conception of the diversity of life in the Early Jurassic, as well as in other ichnofaunas worldwide.

We describe a new enantiornithine specimen from the Lower Cretaceous Jiufotang Formation of the Jehol Biota, northeastern China, which can be assigned to the species Piscivorenantiornis inusitatus. The new specimen confirms the presence of the unusual articulation of the cervical vertebrae that characterizes P. inusitatus. The disarticulated bony elements in the new specimen, some of which are preserved in different views or completely missing from the holotype, enable a more comprehensive morphological reconstruction and a refined phylogenetic assessment of P. inusitatus. The new fossil demonstrates that the occipitals are recessed by a pair of fossae lateral to the foramen magnum, a feature otherwise unknown among Mesozoic and extant birds. Our phylogenetic analysis tentatively resolves P. inusitatus as the sister taxon to the clade consisting of Pterygornis dapingfangensis and Mirusavis parvus, which is recovered deeply nested within the Enantiornithes. We hypothesize that the craniolateral processes of the sternum are a derived feature in enantiornithines.

Probainognathian cynodonts are well represented in the fossil record from the Middle and Upper Triassic of South America, especially in Brazil and Argentina. In this contribution, we describe a new genus and species of non-mammaliaform prozostrodontian cynodont from southern Brazil. The new taxon comes from the Niemeyer Site, a locality in which the traversodontid cynodont Siriusgnathus niemeyerorum is numerically dominant, whereas probainognathians and other tetrapods are comparatively scarce. The fauna from the Niemeyer Site was putatively assigned to the Riograndia Assemblage Zone (Norian age) recently, although none of the index fossils for that biozone (e.g., Riograndia, Clevosaurus, Jachaleria) have so far been discovered at this locality. The new cynodont taxon is based on a left lower jaw with the canine and six (pc2–pc7) well-preserved postcanines (CAPPA/UFSM 0262, holotype), and a second referred specimen (CAPPA/ UFSM 0208, paratype), which includes a right lower jaw with incisors, canine, and seven (pc1–pc7) postcanines, with pc6–pc7 being the best preserved. These specimens have a robust dentary, a long and dorsoventrally tall Meckelian groove, unserrated canines, and unserrated, sectorial postcanine teeth with posteriorly inclined cusps and a poorly developed lingual cingulum. This combination of features is unknown in other Carnian and Norian non-mammaliaform cynodonts. The new taxon contributes to our knowledge of the evolutionary radiation of small prozostrodonts that occurred in western Gondwana during the Late Triassic and led to the emergence of several important cynodont groups, including Mammaliaformes.

The Galericinae are a group of Erinaceidae that are currently distributed in Southeast and Eastern Asia. Although galericines have an Asian origin, their fossil record in this region is scarce, which greatly limits the knowledge of the evolutionary history of this group. We describe here the first fossils of Eulipotyphla from the middle Miocene (13.4–13.2 Ma) of the Mae Moh Basin of northern Thailand, and assign the material to three taxa of Erinaceidae attributable to the Galericinae (Galerix rutlandae, Lantanotherium anthrace, sp. nov., and Lantanotherium sp.). The Mae Moh erinaceids present a Lantanotherium-Galerix association that is uncommon in the Miocene of Asia. Galerix rutlandae is a species formerly described in the Siwaliks of Pakistan and India, which reaffirms the strong affinities during the middle Miocene between the mammalian faunas of Southeast and Southern Asia. The discovery of two species of Lantanotherium in Mae Moh provides additional knowledge about the evolution in Asia of this widespread Miocene genus that had never been recorded in Southeast Asia. The presence of three Galericinae in Mae Moh Basin reinforces the hypothesis of a mainly closed and wet environment during the deposition of the K and Q lignite layers.