Among archosaurs, thalattosuchian crocodylomorphs experienced the most extensive adaptations to the marine realm. Despite significant attention, the phylogenetic position of the group remains uncertain. Thalattosuchians are either the sister-group to Crocodyliformes, basal mesoeucrocodylians, or nest among longirostrine neosuchians. The earliest definite thalattosuchians are Toarcian, and already possess many synapomorphies of the group. All phylogenetic hypotheses imply a ghost lineage extending at least to the Sinemurian, and a lack of older or more plesiomorphic forms may contribute to the uncertain phylogenetic placement of the group. Here we describe a new species, Turnersuchus hingleyae, gen. et sp. nov., from the early Pliensbachian Belemnite Marl Member of the Charmouth Mudstone Formation (Dorset, U.K.). The specimen includes partially articulated cranial, mandibular, axial, and appendicular elements. It can be attributed to Thalattosuchia based on the following features: distinct fossa on the posterolateral corner of the squamosal; broad ventrolateral process of the otoccipital covering the dorsal surface of the quadrate; large supratemporal fenestrae lacking a flattened skull table; broadly exposed prootic; orbital process of quadrate lacking bony attachment with the braincase. This specimen represents the earliest thalattosuchian currently known from diagnostic material. Phylogenetic analyses of two published datasets recover Turnersuchus as the earliest diverging thalattosuchian, and sister to Teleosauroidea + Metriorhynchoidea. Bayesian tip-dating analyses suggest a Rhaetian or Sinemurian divergence of Thalattosuchia from other crocodylomorphs, depending on topology, with confidence intervals spanning from the Norian to the Pliensbachian. The new specimen extends the fossil record of Thalattosuchia, but the time-scaling analyses demonstrate that a significant ghost lineage remains.

Malleodectes? wentworthi, sp. nov. is a highly specialized durophagous marsupial from a Middle Miocene limestone cave deposit in the Riversleigh World Heritage area, northern Australia. It provides the first information regarding the lower dentition of malleodectids, an extinct family of dasyuromorphians. It is also the smallest durophagous member of Metatheria (marsupials and their stem relatives) known to date, with an estimated body mass of ∼70–90 g, an order of magnitude smaller than other known malleodectids (Malleodectes mirabilis and Ma. moenia ∼1 kg). As in other malleodectids, Ma.? wentworthi has a hypertrophied, dome-like premolar specialized for crushing hard foods. Tentative assignment to the genus Malleodectes is based on derived similarities of the premolar and molar dentition to those of larger species of Malleodectes (known only from upper dentitions), and occlusal compatibility. Quantitative morphofunctional analyses of dental indices and mandibular bending strength are congruent with the previously proposed hypothesis that malleodectids may have been uniquely specialized snail-eaters. Maximum parsimony phylogenetic analysis of a 173 morphological character dataset, with a molecular scaffold enforced, placed Ma.? wentworthi within Dasyuromorphia, in a basal polytomy with Dasyuridae and Mutpuracinus archibaldi, to the exclusion of Barinya wangala, Myrmecobiidae and Thylacinidae. Bayesian analysis of a total evidence dataset that combined morphological with nuclear and mitochondrial DNA sequence data places Ma.? wentworthi as a sister taxon to crown-clade Dasyuridae, although support for this relationship is weak.

The Ektopodontidae are an enigmatic group of phalangeroid marsupials known from the late Oligocene to the Early Pleistocene of Australia. Although represented to date only by isolated teeth and several partial dentaries and maxillae, their highly distinctive dental morphology has allowed three genera and nine species to be distinguished. Here, we describe possibly the geologically oldest ektopodontid, Chunia pledgei sp. nov., from the Oligocene Pwerte Marnte Marnte fossil locality of central Australia. Phylogenetic analyses of Phalangeroidea, using 80 primarily dental characters framed by a molecular scaffold, support placement of the new taxon in the genus Chunia. The analyses failed to recover species of the genus Durudawiri in a monophyletic Miralinidae, indicating that they require systematic review. We also transfer the purported basal phalangerid Eocuscus sarastamppi to Miralinidae (Miralina sarastamppi comb. nov.). Additionally, the M1 specimens used to describe the Early to Middle Miocene miralinid genus Barguru, and three species therein, are re-identified as deciduous third premolars from early macropodoids. These findings imply that the Miralinidae are known only from the late Oligocene, whereas the oldest named phalangerids are from the Early Miocene. From a functional consideration of ektopodontid dental morphology, we infer support for prior suggestions of a granivorous and/or frugivorous diet for them. The relative stage-of-evolution expressed by the new taxon is comparable to those in the lower faunal zones of the Namba and Etadunna formations, which supports a late Oligocene age for the Pwerte Marnte Marnte assemblage.

A new genus and species of stromateiform fish, Butyrumichthys henricii gen. et sp. nov., from the Eocene Fur Formation of Denmark is described. The description is based on six well-preserved, almost complete articulated skeletons plus a well-preserved head. All the specimens originate from the carbonate concretion horizons of the Fur Formation. The fossils were investigated also through element-mapping of strontium and phosphorus using a micro-XRF spectrometer in order to expose and enhance the skeletal anatomy. Butyrumichthys gen. nov. exhibits a unique combination of characters that support its recognition as a new stromateoiform genus, including jaws with uniserially arranged, small conical teeth, preopercle with at least 15 prominent spines, 37–38 (17–18 + 20) vertebrae, dorsal fin with 5–6 weak spines and 27–28 soft rays, and anal fin with two spines and 19–20 soft rays. The new fossil stromateoid described herein shows several morphological similarities to certain species of the genus Schedophilus Cocco, 1839, especially S. pemarco (Poll, 1959) and S. medusophagus (Cocco, 1839), and is tentatively referred to the family Centrolophidae. The exceptionally preserved fossil fishes of the Fur Formation increase our knowledge of the diversity of Paleogene marine teleosts, also providing some of the earliest occurrences of modern lineages based on articulated skeletal remains, including that of the stromateiforms.

Nythosaurus larvatus was one of the first non-mammalian cynodonts to be described, and has played a prominent role in the history of paleoneurology as one of the only representatives of this grade to preserve a natural brain endocast. However, the anatomy and relationships of this taxon are obscure, in large part because the only known specimen is incomplete and partially mouldic. Recent literature has generally treated this taxon as either dubious or synonymous with the best-known Early Triassic cynodont, Thrinaxodon liorhinus. Here, we redescribe N. larvatus based on µCT imaging of the holotype NHMUK PV R1715, revealing the never-before-seen and reasonably well-preserved palate and braincase of this specimen. We demonstrate that Nythosaurus is a distinct taxon, differing from Thrinaxodon in its dental morphology, incomplete secondary palate, and bony labyrinth morphology, in which the posterior semicircular canal is the longest of the three semicircular canals. Inclusion of Nythosaurus in a phylogenetic analysis indicates that it represents a basal epicynodont.

A nearly complete skull and limited postcrania (SDSNH 146624), from the upper Oligocene of the Pysht Formation (Clallam County, Washington State, U.S.A.), represent a new species of Pinnarctidion, a pan-pinniped previously restricted to California and Oregon. Here, we describe SDSNH 146624 in detail and present results of a comprehensive phylogenetic analysis of early-diverging pan-pinnipeds. Pinnarctidion iverseni sp. nov., recognized on the basis of this specimen, is diagnosed by its posteriorly broad palate, anteriorly narrow rostrum, dorsoventrally deep zygomatic arches, and posterior accessory cusps on P3–4. Phylogenetic analysis recovered P. iverseni as most closely related to P. bishopi from the Jewett Sand of California's Central Valley. The well-preserved and reasonably complete skull and upper dentition of SDSNH 146624 help clarify relationships among the proximal outgroups of crown clade pinnipeds.

Herein we describe phytosaurs from thin fluvial overbank sandstones of the Upper Triassic Malmros Klint Formation of the Fleming Fjord Group (central East Greenland). The new sample includes more than 150 disarticulated bones and teeth from small to large specimens belonging to at least four individuals. The fossils mostly consist of teeth and postcranial elements and permit the recognition of a new species of Mystriosuchus, M. alleroq, diagnosed by an L-shaped quadratojugal whose anterior suture trends anterodorsally and a tripartite degree of heterodonty. Humeral diaphyseal histology of one specimen reveals a fairly compact cortex that surrounds a cancellous medullary region followed by a remodeling zone containing scattered secondary osteons. Primary bone tissue is parallel-fibred with a moderate to low vascular density. The cortex is cyclically interrupted by distinct growth marks indicating a seasonal environment. A change in growth rate from moderate to low is documented within the outer cortex, indicating that at least this individual was close to somatic maturity. Mystriosuchus has formerly been known as an exclusively European taxon. The new findings support the European faunal influence in East Greenland during the Late Triassic inferred from other taxa such as temnospondyls and archosaurs. The mid-late Norian age of European Mystriosuchus suggests an additional age constraint for the vertebrate-bearing portion of the Malmros Klint Formation.

Heterodontosauridae is a clade that appears early in the ornithischian fossil record, and includes small-bodied, highly specialized species characterized by an unusual heterodont dentition. Although known from relatively few taxa, the early representation of the clade and unsolved phylogenetic relationships within heterodontosaurids and among early ornithischians implies that novel information has a marked effect on broader phylogenetic hypotheses and our understanding of early diversification patterns within Ornithischia. This paper describes the cranial osteology of the heterodontosaurid Manidens condorensis based on computed micro-tomographic scans of MPEF-PV 3211 and MPEF-PV 3809. This enabled more detailed descriptions of previously recognized bones, corrections to the literature, and the identification of undescribed elements. We present a new skull reconstruction and propose an emended diagnosis in light of novel anatomical information. Areas of jaw muscle attachment were identified and compared with Heterodontosaurus and Lesothosaurus, and mandibular function among heterodontosaurids is discussed. Our results indicate that diverse skull morphologies and functions existed among Early Jurassic ornithischians, with Manidens being intermediate between the plesiomorphic cranial shape and function associated with a generalist diet in ornithischians such as Tianyulong and Lesothosaurus, and the more derived cranial construction specialized for herbivory identified in heterodontosaurids from South Africa such as Heterodontosaurus.