The insectivore and marsupial assemblage from the Banovići Basin (MP30/MN1, Bosnia and Herzegovina) provides, in addition to the Rodentia, a better understanding of the faunal exchange between Europe and Anatolia and the biostratigraphic, paleoecological, and paleobiogeographic interpretations of the area. The small and rather poorly preserved collection of fossil remains of insectivores and marsupials from Banovići includes three genera of Talpidae, three genera of Soricidae, one genus of Erinaceidae, one genus of Heterosoricidae, and one marsupial. At the genus level, this assemblage is a mix of genera known from the late Oligocene—early Miocene of Europe (MP29–MN3) and Anatolia (∼MP30–MN3). The presence of the talpids Suleimania aff. ruemkae and Desmanodon aff. ziegleri indicates an age within the Oligocene/Miocene boundary interval (MP30/MN1), which is consonant with the age estimate based on the rodents and magnetostratigraphy. The diversity of Soricidae and the presence of Geotrypus indicate that the Banovići biotope was rather warm and humid during the late Oligocene.

The lower jaw of a gymnodont fish collected from the lower Eocene Cambay Shale Formation in Gujarat Province, western India, has fused dentaries without a beak and a remarkable series of teeth that are unique among all known fossil and living Tetraodontiformes. The teeth are molariform, with raised spokes radiating inward from the emarginated peripheral edge of the crown. Tooth development is intraosseous, with new teeth developing in spongy bone before they erupt and attach to the dentary by pedicels. Although many of the 110 tooth loci in the fossil have lost their teeth, in life the teeth would have grown to fit tightly together to form a broad and continuous crushing surface. The estimated age of the Cambay Shale vertebrate fauna is ca. 54.5 Ma, making the jaw the second oldest confirmed gymnodont fossil. Preliminary comparisons with extant taxa of gymnodonts with fused dentaries (e.g., Diodon, Chilomycterus, and Mola) show detailed similarities in jaw structure, but further study of the dentition is needed to better understand the evolutionary position of the new fossil. We describe the new gymnodont as †Avitoplectus molaris, gen. et sp. nov., in †Avitoplectidae, fam. nov., and place the family as incertae sedis within Gymnodontes.

Seymour Island, Antarctic Peninsula, is known for its wealth of fossil remains. This island provides one of the richest fossiliferous Paleogene sequences in the world. Chondrichthyans seemingly dominate this Eocene marine fauna and offer a rare insight into high-latitude faunas during the Palaeogene. So far, only a few isolated teeth of carcharhinid sharks have been reported from Seymour Island. Bulk sampling in the well-exposed La Meseta and Submeseta formations yielded new and abundant chondrichthyan material, including numerous teeth of carcharhinid and triakid sharks. Here, we present a reevaluation of the previously described carcharhinid remains and a description of new taxa: Meridiogaleus cristatus, gen. et sp. nov., Kallodentis rythistemma, gen. et sp. nov., Abdounia richteri, sp. nov., and Abdounia mesetae, sp. nov. The carcharhiniforms Mustelus sp. and Galeorhinus sp. are reported based on rare material, whereas teeth previously assigned to Scoliodon represent a nomen dubium.

Kelemejtubus castroi, gen. et sp. nov., is described based on six specimens from the marine Danian deposits exposed in the Belisario Domínguez and División del Norte quarries, both located near Palenque City, Chiapas, México. Kelemejtubus castroi shows sufficient features to support its inclusion into the series Percomorpha and is diagnosed by the unique combination of an elongated maxillary, reaching the posterior portion of the orbit; the premaxillary and dentary bearing a row of stout conical teeth; an anterior longer canine-like tooth in the lower jaw; no supramaxillary; preopercle with three antrorse spines on its ventral portion; opercle with two posterior spines; absence of dorsal and anal fin stays; two slightly separated dorsal fin lobes, the first with nine spines and the last with one spine plus nine rays; an anal fin composed of two anal spines and seven soft rays; one supernumerary spine on the first anal pterygiophore; 24 vertebrae, with 10 being abdominal; a caudal fin formula I 8-7 I; three epurals; and a slightly forked posterior ventral procurrent ray with a spur. The absence of unique derived characters, however, does not allow its assignment to any subgroup; thus, it is considered here as a percomorph incertae sedis. This taxon increases the knowledge about the fish assemblage that lived in marine environments at the extreme south of North America approximately 63 million years ago, just after one of the most catastrophic massive extinctions responsible for drastic changes in biodiversity.

The best-preserved material of Dracaenosaurus croizeti, an almost complete and previously unpublished skull with a few associated postcranial bones (stylopodium, zeugopodium, and cervical vertebra), is described. The material comes from the locality of Cournon, a late Oligocene site in south-central France. Micro-computed tomography applied to this specimen revealed previously unknown internal osteological characters. Among lacertids, this taxon represents a notable phenomenon: it is an extreme durophagous specialist. Many of the newly observed cranial character states reflect the lifestyle of this lizard, because animals with a hard-shelled diet display a specialized cranial morphology associated with more massive cranial muscles. One unique character for Lacertidae is observed: the parietal-supraoccipital contact is formed by a ventrally deep parietal crest that fits into a bifurcate ascending process of the supraoccipital. In fact, such a connection represents the opposite to the connection in modern members of Lacertidae. Phylogenetic analysis recovered Dracaenosaurus inside Gallotiinae, a clade that would consist of the mainly Oligocene genera Pseudeumeces and Dracaenosaurus, the Miocene genus Janosikia, and the extant Psammodromus and Gallotia. Our study supports previous phylogenetic results and provides an example of the achievement of large size in mainland members of the stem of Gallotia, previously exemplified by Janosikia and Pseudeumeces. The extreme amblyodonty of Dracaenosaurus also confirms the view that herbivory in Gallotia is derived and may be the result of insularity.

Omphalosaurus is an enigmatic marine reptile of probable ichthyosaurian affinities known from Early and Middle Triassic marine deposits of the Northern Hemisphere. Based on its unique crushing dentition combined with elongate jaws, Omphalosaurus appears to have been a specialized ammonoid feeder. Here we describe a jaw fragment from the Lower Muschelkalk of Silesia, Poland (Karchowice Formation, Anisian, Pelsonian/early Illyrian), and assign it to Omphalosaurus sp. based on tooth morphology, tooth replacement pattern, enamel surface morphology, and enamel microstructure. This is the first record of Omphalosaurus from shallow marine carbonates and from the Muschelkalk facies, a classical source of Middle Triassic marine reptiles. The discovery is unexpected because all other records of Omphalosaurus are from openwater deposits rich in ichthyosaurs and ammonoids. We reidentify an earlier putative record of Omphalosaurus from the Lower Muschelkalk of Rüdersdorf near Berlin, Germany, as the left maxilla of the common Muschelkalk placodont Placodus. This reidentification is based on shared characters of osteology, dentition, mode of tooth replacement, and tooth enamel microstructure. Data on both specimens were collected using visual inspection, micro-computed tomography (µCT), and scanning electron microscopy.

Dinomyidae is a South American caviomorph family that was a very diverse group starting in the Miocene, but is now represented by a single species, Dinomys branickii Peters, 1873. An exclusive feature of dinomyids, not recorded in other mammals, is the presence of accessory articular structures lateral to the occipital condyles, termed paracondyles. In a 1916 study of †Tetrastylus intermedius Rovereto, 1914, an extinct dinomyid from northwestern Argentina, Carlos Ameghino suggested that the paracondyles enhance the support of a large and heavy head. At present, this is the only proposal to explain the presence of these structures. In order to validate this hypothesis, we performed descriptive, metric osteological analyses, and muscular reconstructions of the occipital and cervical regions of †T. intermedius, D. branickii, and other dinomyids, in a comparative context of rodent diversity. We confirmed that, similar to some other living rodents, D. branickii possesses a relatively large head. Conversely, †T. intermedius possesses a size-proportionate head and has larger paracondyles than D. branickii. Our analyses suggested that fossil dinomyids would have performed more marked sagittal movements than D. branickii, and that paracondyles and the whole occipitocervical configuration of dinomyids are specialized for restriction of movements of the head and neck. We rejected the single previous hypothesis and proposed an alternative and novel one, in which paracondyles, and other occipitocervical traits present in dinomyids, as well as in erethizontids, could be related to restricted movements and linked to ecological convergences for stealthy and slow arboreal locomotion.

A fragmentary skeleton from the Kaiparowits Formation (Upper Campanian) of southern Utah represents a new taxon of chelydroid turtle herein named Lutemys warreni. Lutemys warreni differs from other chelydroids in the presence of a smooth shell, lack of plastral or carapacial fontanelles, and development of a thin, gracile plastron. A maximum parsimony analysis of all Late Cretaceous and early Paleogene chelydroids from Laramidia suggests that L. warreni is the most basal known stem kinosternoid. Lutemys warreni therefore represents the fourth named pan-kinosternoid from the Late Cretaceous western island landmass of Laramidia and the first named pan-kinosternoid from the Kaiparowits Formation. The description of L. warreni increases the taxonomic diversity of the Kaiparowits Formation to 16 turtle taxa, making it one of the most diverse fossil turtle assemblages.

The Hell Creek Formation preserves one of the most intensely studied late Cretaceous terrestrial fossil units. Over 22 dinosaur genera are currently recognized from this unit, but the record of juvenile individuals is surprisingly limited. Here, we document a nestling hadrosaur that represents the first occurrence of an articulated nestling dinosaur skeleton from the latest Cretaceous (late Maastrichtian) of North America. The specimen (UCMP 128181) preserves a partial scapula, nearly complete rib cage, vertebral series from the shoulder to mid-tail, a large portion of the pelvic girdle, and both hind limbs through a combination of bone and/or natural impressions in the concretion. It is assignable to the genus Edmontosaurus based on the shape of the prepubic process, or blade, of the pubis. The specimen represents the earliest ontogenetic growth stage of Edmontosaurus cf. annectens and possesses a femur length of 148 mm. It greatly contributes as a new end member to a sample of associated Edmontosaurus skeletons that is well suited for allometrically testing the hypothesized ontogenetic gait shift in hadrosaurs from bipedal juveniles to quadrupedal adults using individual limb proportions. Although UCMP 128181 does not preserve forelimbs, regressions based on associated Edmontosaurus skeletons (N = 25) reveal overall isometry of the forelimb relative to the hind limb, and within each limb. These data indicate that Edmontosaurus nestlings were anatomically capable of fully quadrupedal locomotion and provide no compelling evidence to support an ontogenetic gait shift in hadrosaurids.

We describe a partial skeleton of a new stem group representative of the Sphenisciformes from the mid- Paleocene Waipara Greensand in New Zealand, which represents the best-preserved and most complete Paleocene penguin found so far. Sequiwaimanu rosieae, n. gen. et sp., is the fourth penguin species from the Waipara Greensand, which previously yielded two species that were assigned to the taxon Waimanu, in addition to leg bones of an unnamed giant penguin. Among other features, the new species is characterized by an articular facet for the furcula on the apex carinae of the sternum, which is unknown from other sphenisciforms. We perform detailed comparisons with the species assigned to Waimanu and show that the type species Waimanu manneringi differs in tarsometatarsus morphology from its putative congener ‘W.’ tuatahi, which is here assigned to the new taxon Muriwaimanu. Sequiwaimanu rosieae exhibits a more derived morphology than Muriwaimanu tuatahi, but its exact affinities to W. manneringi are unresolved owing to the incompletely known osteology of the latter species. With S. rosieae being more closely related to the crown group than M. tuatahi, shared characteristics of the two taxa are likely to be plesiomorphic for sphenisciforms. Although the skeletal morphology of these sphenisciform stem species shows some similarities to plotopterids (i.e., wing-propelled diving seabirds from the North Pacific Basin) in some characters, the stem group sphenisciforms from the Waipara Greensand are clearly distinguished from plotopterids.

Dicynodonts were one of the most diverse and abundant clades of tetrapods from the Lopingian (late Permian) to the Late Triassic. Despite their ecological and biostratigraphic importance, the early evolutionary history of dicynodonts is not well understood. Six skulls belonging to the poorly known dicynodont Abajudon kaayai were recently collected from the Guadalupian (middle Permian) lower Madumabisa Mudstone Formation of Zambia. The skulls exhibit characters of endothiodonts, emydopoids, and basal dicynodonts that are not preserved in the holotype from the Ruhuhu Formation of Tanzania. Here we describe the anatomy of the Zambian specimens and use this information in a revised phylogenetic analysis of Permian and Triassic dicynodonts. Abajudon kaayai is found to be the sister taxon of Endothiodon. Endothiodontia is reconstructed as the sister group of Therochelonia, with Emydopoidea placed at the base of Therochelonia. This phylogenetic arrangement helps to explain the mosaic of endothiodont and emydopoid features seen in A. kaayai and in taxa such as Niassodon and Cryptocynodon. The presence of A. kaayai in both the lower Madumabisa Mudstone and Ruhuhu formations allows for the first biostratigraphic correlation of the two strata. The absence of this species in contemporaneous South African Karoo deposits suggests that the early evolutionary history of endothiodont dicynodonts took place outside of the main Karoo Basin.

Two new species of fossil hamsters (Cricetinae, Cricetidae) collected from early Pliocene sediments (∼4.4 Ma) in the Zanda Basin, southwestern Tibet (China), demonstrate greater past diversity among cricetines in the hinterland of the Tibetan Plateau within the Himalayan Range (beyond the previously known ‘Plesiodipus’ thibetensis from the late Miocene of the Gyirong Basin). The occurrence of Nannocricetus qiui, sp. nov., in the Zanda Basin indicates a dispersal of Nannocricetus from its center of origin in northern and northwestern China and the Mongolian Plateau, into the hinterland of the high-elevation Tibetan Plateau and subsequently into the Himalayan Range. The new taxon Aepyocricetus liuae, gen. et sp. nov., possibly represents a specialized (and endemic) Neogene hamster from the Tibetan Plateau. The dispersal of these hamsters into the high-elevation portions of Tibet during the early Pliocene contrasts with the hypothesized biogeographic shift of several large mammal lineages out of Tibet. The absence of Aepyocricetus and Nannocricetus from adjacent portions of the south slope of the Himalayans (and the Siwalik Hills in India and Pakistan) further implies that the Himalayan range functioned as a dispersal barrier for these small mammals by the early Pliocene.