The fossil record of odontocetes (toothed cetaceans) is relatively scarce during the Oligocene and early Miocene compared with later in the Miocene and Pliocene; most of the odontocete families from these epochs are known by a limited number of species and specimens. Among those, Squalodelphinidae is a family of small- to medium-sized platanistoids with single-rooted teeth, which until now has included only four genera based on diagnostic material, from the early Miocene of Europe, Argentina, and North America. Recent field work in the Pisco-Ica desert, southern coast of Peru, has resulted in the discovery of several marine vertebrate-rich localities in various levels of the late Oligocene-early Miocene Chilcatay Formation. Based on three specimens from Ullujaya and Zamaca, including two well-preserved skulls with periotics, we describe a new squalodelphinid genus and species, Huaridelphis raimondii. This new species increases the early Miocene diversity of the family and is also its smallest known member. It further differs from other squalodelphinids by its thin antorbital process of the frontal, abruptly tapering rostrum, and higher tooth count. A more fragmentary skull, from Zamaca, is referred to Squalodelphinidae aff. H. raimondii. This skull provides information on the morphology of the tympanic, malleus, and incus, currently unknown in H. raimondii. Focusing on platanistoids with single-rooted teeth, our phylogenetic analysis suggests that Squalodelphinidae are monophyletic and confirms the sister-group relationship between the latter and Platanistidae. The relationships within Squalodelphinidae are not fully resolved, but H. raimondii might be one of the earliest diverging taxa.

Toadfishes (Batrachoidiformes) are benthic fishes often burying in the sand or under rocks that occur worldwide in tropical to temperate marine and brackish waters. The Batrachoididae, the only known family of the order Batrachoidiformes, includes 23 extant genera and about 80 species arranged in four subfamilies. A new genus and species of toadfish, †Zappaichthys harzhauseri, gen. et sp. nov., is described from the middle Miocene (upper Badenian) Leitha Limestone of St. Margarethen in Burgenland, Eisenstadt-Sopron Basin, Austria. It is based on three partially complete, well-preserved articulated skeletons plus a neurocranium that display a unique combination of characters [possession of 29 (10 19) vertebrae; dorsal fin with three solid spines and 16 rays; anal fin with 11 rays; pectoral fin with 20–25 rays; interorbital region of the neurocranium wide; postorbital sector of the neurocranium longer than the orbital one; four ossified pectoral-fin radiais; opercle with a strong pointed spine; subopercle bearing two spines and two short filaments; scales absent] that support its recognition as a new genus of the family Batrachoididae. †Zappaichthys harzhauseri, gen. et sp. nov., is the oldest member of the Batrachoidiformes known to date based on articulated skeletal remains. The fossil record of batrachoidiform fishes is discussed in detail.

The spectacularly fossiliferous Calvert Formation is largely exposed in Maryland and Virginia and comprises the best available record of middle Miocene life in the northeastern United States. Lopholatilus ereborensis, sp. nov., a new tilefish from the middle Miocene (Langhian) of the Calvert Formation, is described herein based on 15 well-preserved three-dimensional partially complete articulated skeletons. These fossils consist primarily of cranial remains and represent the earliest known occurrence of the genus Lopholatilus in the record. Lopholatilus ereborensis is characterized by moderately deep head and short snout, occipital region of the neurocranium obliquely sloping, epioccipital spine extending posteriorly beyond the supraoccipital crest, remarkably shortened ascending process of the premaxilla, villiform teeth on dentary restricted to the symphyseal region, horizontal arm of the preopercle short, and angle formed by vertical and horizontal arms of the preopercle measuring about 120°. Taphonomic and paleoecological considerations suggest that Lopholatilus ereborensis inhabited long funnel-shaped vertical burrows self-excavated within the stable and cohesive bottoms of the outer continental shelf of the Salisbury Embayment, and possibly of other parts of the western North Atlantic outer shelf and upper slope that were characterized by relatively warm oxygenated waters. In that context, the three-dimensional preservation of the articulated skeletons of Lopholatilus ereborensis might represent the product of an abrupt burial resulting from the collapse of the upper part of the burrows. Cylindrical-shaped trace fossils (domichnia) penetrating the fine-grained sands of the middle part of the Calvert Formation are proposed to have been produced by Lopholatilus ereborensis.

Description of a new species of the parareptile genus Delorhynchus is based on a well-preserved partial subadult skeleton, an isolated adult skull, and disarticulated elements recently collected from the Lower Permian Richards Spur locality of Oklahoma, U.S.A. Delorhynchus cifellii, sp. nov., is distinguished from Delorhynchus priscus by the lack of an accessory articulating anterodorsal flange of the maxilla. The hypodigm of Delorhynchus cifellii reveals that Delorhynchus is distinguished from other parareptiles by cranial dermal sculpture consisting of a system of low, smooth tuberosities and a pattern of diffuse shallow, circular dimples. In a phylogenetic analysis of parareptiles, Delorhynchus cifellii is positioned as the sister species of Lanthanosuchoidea. Recognition of Delorhynchus cifellii. sp. nov., and its phylogenetic position among parareptiles highlights the significance of the Richards Spur locality in our understanding of the early evolutionary history of reptiles.

Records of Early Triassic marine reptiles, when they first emerged after the end Permian mass extinction, are rare. During an excavation at Majiashan, Chaohu, Anhui Province, a new sauropterygian specimen was found co-occurring with the ichthyopterygian Chaohusaurus from the Upper Member of the Nanlinghu Formation, of Olenekian (Spathian, Early Triassic) age, for which a new taxon, Majiashanosaurus discocoracoidis, gen. et sp. nov., is erected. This skeleton is exposed in ventral view, with the last three cervical vertebrae together with 19 dorsal, three sacral, and more than 18 caudal vertebrae preserved. The cervical centra are keeled ventrally, and cervical ribs are double-headed, carrying a free anterior process. The transverse processes of the dorsal vertebrae are not distinctively elongated. The dorsal ribs are single-headed, and the clavicles articulate on the anteromedial aspect of the scapula. The humerus is curved. These features allow assignment to a new sauropterygian taxon. The interclavicle has no posterior process, and the scapula is of typical eosauropterygian shape, with a broad and ventrally expanded glenoidal portion that is separated from a narrow posterodorsal blade by a distinct constriction. The coracoid is round and plate-like without a waist. This feature is different from that of all other known eosauropterygians, but resembles that of placodonts.

We describe the syntype postcranial skeletons of the cryptoclidid plesiosauroid Colymbosaurus megadeirus. C. megadeirus is the type species of Colymbosaurus, and one other valid species, C. svalbardensis, is known. Although it is in widespread usage, C. trochanterius is a not valid species, although the presence of an anteroposteriorly oriented ridge bisecting the distal surfaces of the holotype humerus allows its referral to Colymbosaurus sp. Some specimens previously referred to C. trochanterius, including the holotype of ‘Plesiosaurus’ manselii, lack this feature, or show other differences from our hypodigm, suggesting that they are taxonomically distinct from Colymbosaurus, and countering previous suggestions that the Kimmeridge Clay Formation represents a depauperate plesiosauroid fauna. Substantial differences between the atlas-axis complexes and cervical vertebrae of Kimmerosaurus langhami, ‘Plesiosaurus’ manselii, C. megadeirus, and specimens referred here to cf. Spitrasaurus indicate that at least four plesiosauroid taxa were present in the Kimmeridge Clay Formation. This proposition is also supported by coracoid morphotypes, and demonstrates that Late Jurassic plesiosauroids were taxonomically diverse. Most Late Jurassic-Early Cretaceous cryptoclidids belong to a monophyletic Colymbosaurinae, but Kimmerosaurus and its sister taxon Tatenectes originated independently from Middle Jurassic cryptoclidids.

The first described genus of mosasaur, Mosasaurus hoffmannii, has been coarsely diagnosed and defined since its creation, with numerous specimens and new species being assigned to the genus with little or no reference to, and thus few real similarities with, the generic type specimen. One of the earliest examples of a weakly defined and diagnosed species assigned to the genus is Mosasaurus gracilis. Location and examination of the various assigned specimens and the holotype indicate that M. gracilis shares more characters, such as a short rostrum on the dentary anterior to the first teeth, with russellosaurine mosasaurs. In addition, M. gracilis is known from Turonian deposits, whereas other species belonging to Mosasaurus are upper Campanian—Maastrichtian in age. Based on the evidence of shared characters and contemporaneity, we suggest that M. gracilis be removed from Mosasaurus because it shares more affinities with members of the Russellosaurina. This represents the first step in the very necessary process of untangling the alpha taxonomy, and subsequently the complete systematics, of the genus Mosasaurus hoffmannii.

We describe three new fossil snakes on the basis of recently discovered vertebrae collected from the Upper Cretaceous (Maastrichtian) Maevarano Formation of Madagascar. One represents a new genus and species of madtsoiid, Adinophis fisaka, the third member of this family recognized from the Maevarano Formation. It exhibits dorsoventrally compressed centra and dorsally placed synapophyses. The second taxon is a new species of the nigerophiid genus Indophis, I. fanambinana, representing the second nigerophiid taxon known from the Maevarano Formation. It shares numerous features with the Indian nigerophiid I. sahnii, including small synapophyses positioned ventrolaterally on distinct synapophyseal processes and a unique cotylar shape in posterior trunk vertebrae. The discovery of I. fanambinana demonstrates a strong biogeographic link with penecontemporaneous snake faunas from India. A third new taxon is represented by a partial centrum that cannot be assessed thoroughly due to its incompleteness; this specimen is conservatively assigned to Serpentes incertae sedis, gen. et sp. indeterminate. It is distinct from other snakes known from the Late Cretaceous of Madagascar in possessing a strongly depressed condyle and relatively large lateral foramina. These new discoveries, together with previous descriptions of snakes from the Maevarano Formation, make the Maevarano snake fauna one of the most taxonomically diverse snake assemblages known from the Mesozoic and the most diverse in terms of body size range.

Early Miocene deposits from the Domo de Zaza locality, in the south-central Cuban province of Sancti Spiritus, preserve crocodyliform remains, including compressed serrated teeth closely resembling those of South American sebecids. Fragmentary cranial and mandibular material is more difficult to assess. Referral to any other post-Paleogene crocodyliform known from the Western Hemisphere can be ruled out, and phylogenetic analyses are unable to pinpoint its relationships. Similarities can be found with planocraniids, including ventrally oriented and mediolaterally expanded orbital surfaces, but the morphology of the quadrate is inconsistent with a planocraniid affinity. A sebecid in the Miocene of Cuba would be congruent with evidence from other vertebrates suggesting extensive dispersal between the Greater Antilles and South America during the Neogene, and it would be the first Neogene record of the group outside South America. The other crocodyliform may indicate the presence of an endemic West Indian lineage not closely related to any contemporaneous group. It is also consistent with extant Crocodylus arriving in the Neotropics within the past 5–10 million years.

A new dryosaurid ornithopod, Eousdryosaurus nanohallucis, gen. et sp. nov., is described here based on a single specimen from the Late Jurassic Alcobaça Formation of Portugal. Eousdryosaurus nanohallucis is distinguished from all other dryosaurids by eight autapomorphic features and an unique combination of characters, some of which are also shared by other dryosaurids. Eousdryosaurus is linked with Dryosauridae, because the fourth trochanter is proximally placed and widely separated from the scar for the insertion of the M. caudifemoralis longus, which is restricted to the medial surface of the femoral shaft. Phylogenetic analysis nests Eousdryosaurus in an unresolved polytomy at the base of Dryosauridae together with Callovosaurus, Dryosaurus, and Kangnasaurus. The complete pes of Eousdryosaurus, which has a phalangeal formula of 1-3-4-5-0, supports the putative autapomorphic reduction of the dryosaurid pes that also occurs in parallel in more derived ornithopods.

The cranial anatomy of the basal sauropodomorph Coloradisaurus brevis from the upper levels of the Norian Los Colorados Formation is here redescribed and comparisons made based on the holotype skull and mandible. Coloradisaurus brevis is diagnosed by most of the features proposed in the original description and an additional set of autapomorphies, such as presence of circular upper temporal fenestrae, laminae on the ventrolateral margins of a ventral fossa of the basisphenoid and on the ventral region of the parasphenoid, and tab-like medial process at the posteromedial end of the mandible. Coloradisaurus is placed within Massospondylidae, as in recent analyses. This position is supported primarily by postcranial characters, but some cranial features identified in this study provide additional evidence supporting this position (e.g., jugal contribution to the antorbital fenestra, frontal proportionately longer than nasals). However, the cranial anatomy of Coloradisaurus also bears several characters that are shared with plateosaurids (e.g., low mandibular articulation, broad maxillary wall on the anterior margin of antorbital fossa, broad prefrontals, projection of infratemporal fenestra behind the orbit, stepped braincase, robust septum between basipterygoid processes). Thus, Coloradisaurus is interpreted as a massospondylid that has convergently acquired characters that are otherwise only known in plateosaurids, highlighting the conflicting pattern of character distribution among basal sauropodomorphs.

Whereas titanosaurians represent the most diverse and cosmopolitan clade of Cretaceous sauropod dinosaurs, they remain rare components of Cretaceous African faunas. Currently recognized continental African titanosaurians include Aegyptosaurus baharijensis and Paralititan stromeri from early Upper Cretaceous deposits near Bahariya Oasis, Egypt, and Malawisaurus dixeyi and Karongasaurus gittelmani from the Lower Cretaceous (∼Aptian) Dinosaur Beds of Malawi, in addition to several undesignated and fragmentary forms across the continent. Here, we describe a new titanosaurian taxon, Rukwatitan bisepultus, on the basis of a partial, semiarticulated postcranial skeleton recovered from the middle Cretaceous Galula Formation in southwestern Tanzania. Unique to Rukwatitan are carotid processes on posterior cervical vertebrae, a deep coracobrachialis fossa and subquadrangular cross-section of the humerus, and a slender, curved, teardrop-shaped pubic peduncle on the ilium. Parsimony and Bayesian phylogenetic analyses of 35 sauropod taxa congruently place Rukwatitan as a non-lithostrotian titanosaurian, a relationship supported by cervical vertebrae with undivided pleurocoels and strongly procoelous anterior caudal vertebrae. Rukwatitan differs from the potentially penecontemporaneous and geographically proximate Malawisaurus by exhibiting weakly developed chevron articulations and posteriorly inclined neural spines on the middle caudal vertebrae, a proximally robust and distally unexpanded humerus, and an anteroventrally elongated coracoid. Similar to biogeographic patterns identified in certain crocodyliform clades (e.g., small-bodied notosuchians), titanosaurians on continental Africa appear to exhibit a regional (e.g., southern versus northern Africa), rather than a continental- or supercontinental-level signal.

Geological investigation of the Boyabat Basin in north-central Anatolia, Turkey, yielded palaeoamasid (Embrithopoda, Mammalia) gnathodental fossil specimens from two localities dated to the Eocene—Oligocene transition. These specimens include an upper incisor (BOY-1) and maxillary fragment preserving M2–M3 (BOY-2), and are geologically the youngest embrithopods known from Eurasia. The maxillary specimen is taxonomically more useful and, among embrithopods preserving the same molars, is most similar to the late Paleocene—middle Eocene Turkish palaeoamasid Palaeoamasia kansui. However, the new specimens are cautiously classified as Palaeoamasia. sp. nov., based on distinctions between BOY-2 and P. kansui in M3 morphology. Features distinguishing the M3 in BOY-2 are intermediate between those of P. kansui and the more derived Afro-Arabian arsinoitheriid embrithopods Arsinoitherium spp. and Namatherium blackerowense, although the new Turkish specimens are stratigraphically too young to be ancestral to these middle Eocene—late Oligocene arsinoitheriids. Salient differences in dental and gnathic morphology between contemporaneous Eurasian and Afro-Arabian embrithopods indicate long, separate phylogenetic trajectories for these taxa, supporting the view that they are divisible at the family level into Palaeoamasidae and Arsinoitheriidae, respectively. Improved documentation of the lengthy paleogeographic separation of palaeoamasids and arsinoitheriids confirms that Afro-Arabia was sufficiently isolated from Eurasia during the Paleogene to limit embrithopods to rare sweepstakes dispersal between these landmasses.

Four species of Panochthus (P. greslebini, P. jaguaribensis, P. oliveira-roxoi, and P. rochai) have been described from the late Pleistocene of northeastern Brazil. P. oliveira-roxoi, and P. rochai have been considered loosely as synonyms of P. greslebini. This paper reevaluates the referred material, diagnostic characters, and validity of these species and includes a cladistic analysis of 25 caudal tube and carapace characters to determine their positioning relative to other species of Panochthus. P. greslebini and P. jaguaribensis are valid species and differ from the other species of Panochthus by unique combinations of caudal tube characters. Carapace fragments previously attributed to P. jaguaribensis are in fact fragments of cephalic shields. These fragments and the isolated ostoderms previously described for P. jaguaribensis cannot be confidently assigned to this species. We support the interpretation of P. rochai as a junior synonym of P. greslebini, but P. oliveira-roxoi is actually a nomen dubium instead of a synonym of P. greslebini. Our analysis yielded a fully resolved tree in which Panochthini, as traditionally defined, is paraphyletic and the species formerly attributed to Panochthus form a monophyletic group, echoing recent findings based on a different dataset. Within Panochthus, the Brazilian species form a clade with the Bonaerian species P. subintermedius, which is the sister species to P. greslebini. Instead of a more basal position suggested in early and recent works, P. jaguaribensis is deeply nested within the clade encompassing the species of Panochthus.

Procreodi is an order of Paleocene and Eocene mammals thought to lie at the base of the radiation of the paraphyletic ‘condylarths.’ Taxa within the order have been linked to the origins of other condylarth groups, and of some living orders. Within the order, there are specializations indicative of a range of behaviors, and a considerable size range including some of the largest Paleocene mammals. Arctocyon mumak is the largest known arctocyonid. Several craniodental specimens from the Tiffanian of western North America and one partial skeleton, preserving parts of the fore- and hind limbs, pelvic and pectoral girdles, and some vertebrae, with associated teeth and other bony elements, are described here for the first time. Skeletal elements of A. mumak are larger than those of other species of Arctocyon and Anacodon, but are otherwise similar in overall morphology. Certain features of the tarsus, such as the large plantar tubercle on the navicular and the well-developed groove below the sustentaculum tali, are shared between A. mumak and Anacodon to the exclusion of Artcocyon and are suggestive of plantigrady and a degree of fossoriality. Univariate and multivariate statistical analyses of six ecomorphological ratios successfully distinguishes a taxonomically diverse group of 47 extant taxa with differing locomotor specializations. When calculated for Arctocyon mumak, these ratios support the view that this taxon was a terrestrial, possibly semi-fossorial taxon. Other taxa within Procreodi are recovered as more arboreal or more terrestrial. Significant ecological and morphological variation exists within this understudied group.

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The skull of the Paleocene mammal Radinskya is redescribed here, based on direct study of the type and only specimen. A number of inaccuracies from previous studies are corrected. Radinskya possesses two potential synapomorphies with perissodactyls, namely, posteriorly broad nasals and a small, laterally facing exposure of the mastoid process of the periotic. The phylogenetic position of Radinskya is examined using matrices from three studies, two that originally included Radinskya and for which the scores for Radinskya are corrected, and another recent study of archaic ungulates that did not originally include Radinskya. In addition, a new analysis is performed combining data from all three previous studies, including modifications based on the present study. Reanalyses of the three previous studies give conflicting results regarding the issue of perissodactyl ancestry, placing Radinskya as sister taxon to perissodactyls, as sister taxon to a perissodactyl-phenacodontid clade, or as part of a polytomy with perissodactyls and paenugulates. The results of the new analysis (1) place perissodactyls closer to Radinskya than to phenacodontids; (2) place Hyracoidea and Proboscidea (i.e., Paenungulata) as sister taxa to Perissodactyla; (3) do not support inclusion of Radinskya in Phenacolophidae; and (4) are equivocal in placing Lophocion as the phenacodontid closest to perissodactyls. These results thus support neither an Asian nor a North American origin for perissodactyls. Future studies should examine the origins of perissodactyls and other ‘ungulates’ in a broader taxonomic context, in order to more directly address discrepancies between results supported by morphological data and those derived from molecular data.

Kentriodon hoepfneri, sp. nov., is described from elements of the skull and a nearly complete vertebral column from middle/upper Miocene deposits of Groß Pampau, northern Germany. The new species is distinguished from previously described species of Kentriodon Kellogg, 1927, by anteromedially globular nasal bones and a narrowly elliptical posterior buhar facet of the periotic. In the size of its skull and teeth, overall morphology of the periotic, and the pentagonal shape of the nasal, the new species most closely resembles Kentriodon pernix and the probably congeneric Belgian specimen IRSNB M.372. The proportions of the vertebral centra indicate similarities with extant ziphiid and monodontid cetaceans, with greatest flexibility of the body in the lumbar region. Kentriodon hoepfneri, sp. nov., is the youngest known member of the kentriodontine subfamily to date. Among the subfamily Kentriodontinae, Kentriodon is the only genus with a Transatlantic distribution during the Miocene.

Associated fragments of a maxilla and mandible of Theosodon hystatus Cabrera and Kraglievich (Macraucheniidae, Litopterna) from the late Miocene Arroyo Chasicó locality (Buenos Aires Province, Argentina) are described and taxonomically reinterpreted. The systematic arrangement is supported by the first phylogenetic analysis of the family. The holotype (MLP 29-IX-1-75) of T. hystatus was originally poorly described and its generic assignation was not fully justified. The comparison of MLP 29-IX-1-75 with Paranauchenia denticulata Ameghino from the ‘Mesopotamiense’ (lower member of the Ituzaingó Formation, Entre Ríos Province; late Miocene) shows significant morphological similarities that lead us to propose that T. hystatus belongs to the genus Paranauchenia Ameghino, resulting in the new combination Paranauchenia hystata. The phylogenetic analysis of Macraucheniidae supports this proposal because both taxa form a monophyletic clade, sharing one synapomorphy: metaconid of m2 lingually placed. This new taxonomic interpretation implies the geographic extension of Paranauchenia to Buenos Aires Province. The obtained phylogeny also corroborates the monophyly of Macraucheniidae, but not that of the currently considered subfamilies, because Cramaucheniinae is paraphyetic.