Paleocene deposits of the Tullock Member of the Fort Union Formation, Montana, U.S.A., have yielded several new specimens of †Polyodon tuberculata, a taxon previously described from the formation, as well as a new genus and species of sturgeon (Acipenseridae). The three new specimens of †P. tuberculata allow us to revise and to confirm previously reported features of the holotype, as well as to describe other features that were not preserved in the single specimen previously known. For example, we observe that (1) the left and right posttemporals overlie the left and right parietals to meet in the midline, (2) the posttemporal has a deep ventral flange, and (3) the parasphenoid extends farther posteriorly than the parietals. The new sturgeon is fairly small, and not well preserved. It can be distinguished from all other acipenserids by a combination of features, including kite-shaped dorsal scutes bearing a strong median ridge, lateral scutes that vary in shape from rhomboid to irregularly shaped elements, a large triangular scute behind the anal fin, and numerous small rhomboid scales covering the caudal skeleton. It cannot be included in any currently known genus and is here named †Engdahlichthys milviaegis, gen. et sp. nov.

Early Mesozoic halecomorphs are highly diverse, but their taxonomy and phylogenetic relationships are still controversial. We describe here a new halecomorph taxon from the Late Jurassic (Kimmeridgian) Nusplingen Lithographic Limestone, southern Germany. Sanctusichthys rieteri, gen. et sp. nov., is characterized by the peculiar patterns of skull roofing bones and cephalic sensory canals, and a unique squamation made of tiny lepisosteoid-type scales with extremely or completely reduced ganoin layer. Very peculiarly, S. rieteri presents a series of bones placed between the frontals and the anamestic supraorbitals, one of them carrying a portion of the main supraorbital sensory canal between the frontal and nasal bones. These bones, here called parafrontals, are so far unknown in other actinopterygians. The new taxon resembles most closely several Late Jurassic Furo-like halecomorphs, which have been classified in the family Furidae and are currently placed in either of the controversial orders Ophiopsiformes or Ionoscopiformes. The close phylogenetic relationships between these taxa are confirmed in a cladistic analysis that retrieves Sanctusichthys within a broadly defined Ionoscopiformes, including the potentially independent Ophiopsiformes. Interestingly, these Furo-like halecomorphs are highly diverse in the Late Jurassic deposits of southern Germany, and they are especially well represented—with four species accounting for 15% of the actinopterygian taxa—in the Nusplingen quarry, which yields one of the three most diverse Jurassic assemblages of these fishes. The paleoecological significance of this high diversity can only be explored after solving the β-taxonomy and phylogenetic relationships of these Furo-like taxa.

Clupeids are one of the most diverse groups of marine fishes represented by numerous extant genera and species. The diversity of European clupeids was even greater in the past, especially during the Paleogene and early Neogene. Here we present the results of a thorough revision of numerous fish fossils assigned to the subfamily Clupeinae. They come from Oligocene and early Miocene deposits of the former Eastern Paratethys and the Carpathian Basin, and are represented by complete and fragmented skeletons. A new endemic genus—†Rupelia Baykina and Kovalchuk, gen. nov.—is established for small-sized herrings from the early Oligocene (Rupelian) of the Caucasus. It occurred only in the Eastern Paratethys and was represented by a single species—†R. rata (Daniltshenko, 1959). At that time, another herring inhabited the entire Paratethys. It completely fits into †Clupeonella (Maicopiella) sensu Menner, 1949a—a subgenus which is raised here to genus level. Based on our review, this herring was represented during the Oligocene by †Maicopiella longimana (Heckel, 1850) —a widespread species with numerous fossils found in deposits mostly of Rupelian and partly of Chattian age. †Rupelia rata went extinct at the beginning of the Miocene, while †Maicopiella longimana was replaced by †M. brevicauda (Menner, 1949a) in the Eastern Paratethys and by †Sardinella sardinites (Heckel, 1850) in the Carpathian Basin. A detailed morphological description of all mentioned taxa is presented. The results of our study shed more light on the diversity and distribution of herrings within the central and eastern parts of the Paratethys during the Oligocene and early Miocene.

†Neilpeartia ceratoi, gen. et sp. nov., a new antennariid frogfish, is described based on a single, well-preserved, articulated specimen from the Ypresian of Bolca, Italy. The morpho-anatomical analysis of this nicely preserved fossil reveals a series of features that unambiguously support its recognition as a new member of the lophiiform family Antennariidae, including body extensively covered with tiny, close-set, bifurcated dermal spinules, illicium considerably elongate and broadly spinulose in its lower portion, bulbous esca absent, endopterygoid, epural, and caudal peduncle present; caudal fin with nine branched rays, 19 vertebrae, 13 dorsal-fin rays, eight anal-fin rays, nine pectoral-fin rays, and five bifurcated pelvic-fin rays. †Neilpeartia, gen. nov., is assigned to the subfamily Antennariinae, and seems to form a sister pair with the extant genus Fowlerichthys, which in turn represents the sister clade to all the other antennariine taxa. Consequently, †Neilpeartia ceratoi, gen. et sp. nov., should be regarded as the oldest known unquestionable evidence of crown antennariids in the fossil record. Paleoecological and evolutionary implications are also discussed.

The Upper Cretaceous record of lungfishes from South America is abundant but represented mainly by tooth plates and associated jaw bones. A new dipnoan species from the Upper Cretaceous of the La Colonia Formation, Chubut Province, Argentina, is described here. Metaceratodus baibianorum, sp. nov., is diagnosed by a combination of features (tooth plates from medium to large size, inner angles located at the second cleft in upper tooth plates and at the second ridge in lower ones). Previously, some material of Metaceratodus baibianorum was referred to Metaceratodus wichmanni. However, by applying morphogeometric studies and a statistical analysis to compare means of independent samples, we conclude that Metaceratodus baibianorum, sp. nov., differs from the other species of similar age in Patagonia.

New material from the Upper Devonian (Famennian) Catskill Formation of Pennsylvania, U.S.A., indicates the presence of a new species of Megalichthys. A large collection of complete and well-preserved fossil material from the Red Hill field locality enables a thorough anatomical description that is not commonly available in Megalichthyidae. The cranial material includes skull roof, partial cheek, lower jaw, opercular-gular elements, palatoquadrate, and dermal palatal elements. The postcranial material includes pectoral fin elements including cleithrum, mesomeres, and lepidotrichia; pelvic fin including lepidotrichia; and body scales in articulation. The new species is distinguished from other species of Megalichthys by the presence of a pineal series of bones, a triangular-shaped principal gular, and a lack of sensory canal pores on the postparietal. We review the taxonomic history and status of Megalichthyidae and Megalichthys and provide revised diagnoses for each that include only discrete features demonstrated to be sufficient for taxonomic assignment. We discuss additional cosmine-covered osteolepiform fossils from other Catskill Formation exposures. These include the type and only specimen of Sterropterygion brandei and seven new specimens (including a partial snout, a partial parietal shield, a partial postparietal shield, a partial cheek, and complete lower jaws) that potentially represent megalichthyid species in addition to the one at the focus of this study. With this description of new megalichthyid material, the Catskill Formation continues to produce, in some cases, the only known Devonian occurrence of otherwise younger taxa.

For the first time, the cranial suture pattern for the type species of Cacops, C. aspidephorus, is described in detail. A majority of sutures, including the lower jaw, the skull roof, and the palate, are now known in detail, although details are still lacking for the posterior skull table. Notable new information about C. aspidephorus includes the presence of a lateral exposure of the palatine (LEP), a lateral exposure of the ectopterygoid (LEE) that fuses with the jugal with growth, and a subtympanic flange composed mostly of the supratemporal. Cacops aspidephorus is very similar to C. morrisi, but differences, including a fully closed otic notch in C. aspidephorus, are sufficient to maintain both as distinct species. Uniquely, C. aspidephorus shows palatal dentition of the same size as the marginal dentition, but it remains to be seen whether this is a widespread feature or ontogenetically transient. These new data will finally permit the inclusion of this iconic taxon, described over 100 years ago, into larger-scale phylogenies of dissorophoid and temnospondyl relationships.

Ontogenetic series are rarely preserved in the fossil record, but when present they provide valuable insight into life history, developmental, and evolutionary patterns in extinct taxa. Here, we describe an intact, three-dimensionally preserved skull of Pasawioops mayi (Amphibamiformes, Micropholidae), which has not been fully described previously. Together with the holotype, also an intact skull, these two specimens of Pasawioops are interpreted as part of an ontogenetic series. The two specimens differ in traits that are thought to change during ontogeny in temnospondyls, including elongation of the postorbital region, transformation of the palatal dentition from small groups of denticles to significantly larger teeth, and a posteriorly shifting lower jaw articulation. We survey previously described amphibamiform taxa and use the ontogenetic data derived from Pasawioops to identify other potential ontogenetic series (e.g., Eoscopus). Additionally, we briefly compare amphibamiform ontogenetic series to known ontogenetic data of olsoniform and micromelerpetontid dissorophoids, and other early tetrapod lineages, to determine the extent to which ontogeny may or may not be conserved across these lineages. Several aspects of the ontogeny of Pasawioops are found to be present in lissamphibians and Amphibamiformes (i.e., branchiosaurids and amphibamids), revealing that some ontogeny-dependent traits are highly conserved within this group, whereas others are more broadly conserved across other tetrapod lineages.

This paper provides a description and analysis of cranial remains of a rhynchosaur from the Upper Triassic Evangeline Member of the Wolfville Formation of Nova Scotia, Canada. This material, primarily comprising jaw elements, represents the first definitive record of Late Triassic rhynchosaurs from eastern North America. All cranial bones can be assigned to Hyperodapedontinae. The dentition of the Nova Scotian hyperodapedontine differs from those of Hyperodapedon and Isalorhynchus. The maxilla apparently did not have more than two lateral rows and two medial rows of teeth. The teeth of the lateral row closest to the single groove dividing the maxillary tooth plate are more than twice as large as those of the medial row closest to the groove. The lateral and medial tooth-bearing portions of the maxilla become increasingly crest-like during ontogeny. The dentary lacks a lingual row of teeth. Based on this combination of features, the hyperodapedontine material from the Evangeline Member is assigned to a new taxon, Oryctorhynchus bairdi, gen. et sp. nov., which is the sister species to an unnamed hyperodapedontine taxon from Wyoming. This clade was recovered as the sister taxon to Hyperodapedon spp. in the phylogenetic analysis. The late Carnian or earliest Norian tetrapod assemblage from the Evangeline Member represents a mixture of faunal elements from a wide paleolatitudinal range, suggesting a more cosmopolitan distribution for continental tetrapods during the early Late Triassic than previously assumed.

Bone histology has provided valuable information on the life history of dinosaurs, and the presence of growth lines provides useful information for age estimation, growth variation, and the reconstruction of paleobehavior. Here, we present new data recovered from five individuals of the non-iguanodontian ornithopod dinosaur Jeholosaurus shangyuanensis from the Early Cretaceous Jehol Biota. These specimens, ranging in body length from 16 to 62 cm, represent early juvenile, late juvenile, and subadult ontogenetic stages. The bones of Jeholosaurus mainly consist of fibrolamellar tissue, which is similar to that of other non-iguanodontian ornithopods; however, parallel-fibered bone and lamellar bone tissues were also deposited in early juvenile through subadult individuals, suggesting relatively slow growth rates. Parallel-fibered bone is only regionally present in the juvenile but is well developed throughout the outermost cortex of the subadult. Skeletochronology indicates that these specimens range in age from one to five years old. Analyzing bone tissue distribution and lines of arrested growth (LAGs) in these specimens, we estimate that Jeholosaurus reached sexual maturity at two to four years old. The largest individual (IVPP V15939) displays an apparently higher growth rate during the first two years, which is abruptly reduced in the following years, suggesting a distinct growth pattern that may be related to sexual dimorphism or variable environmental conditions. Finally, the largest specimen displays parallel-fibered bone tissue but lacks an external fundamental system (EFS) near the periphery, suggesting that it was still growing but was approaching somatic maturity at death.

Thecodontosaurus antiquus is a basal sauropodomorph from the Rhaetian locality of Durdham Down in Bristol, U.K. Sauropodomorph material putatively assigned to this species was found at the nearby site of Tytherington. Here, we describe the Tytherington specimens and compare them with T. antiquus and other Late Triassic sauropodomorphs from Britain. We find that this material can be assigned to T. antiquus based on multiple shared morphological traits, and we provide a revised diagnosis of this taxon. The new anatomical information from the Tytherington specimens enriches the osteology of the species, particularly of previously unknown parts of the skeleton such as the skull. We find poor anatomical support to distinguish the contemporary Pantydraco caducus from T. antiquus, such that the former might represent a juvenile of the latter. We also discuss the questionable validity of Asylosaurus yalensis. Thecodontosaurus antiquus is one of the most basal sauropodomorphs that show craniodental traits related to herbivory, while retaining a plesiomorphic limb morphology and posture. This taxon was an important component of Rhaetian insular ecosystems of southwestern Britain.

We describe a partial skeleton of a large-sized owl from Wasatchian strata of the Willwood Formation (Wyoming, U.S.A.). The holotype of Primoptynx poliotauros, gen. et sp. nov., includes all major postcranial bones and is one of the most substantial Paleogene records of the Strigiformes. The fossil shows that owls exhibited a considerable morphological diversity in the early Eocene of North America and occupied disparate ecological niches. As in the protostrigid taxon Minerva from the late early to early middle Eocene of North America, but unlike in extant owls, the ungual phalanges of the hallux and the second toe of the new species are distinctly larger than those of the other toes. Primoptynx poliotauros gen. et sp. nov., however, does not exhibit the derived tibiotarsus morphology of the Protostrigidae. Even though the new species may well be a stem group representative of protostrigid owls, current data do not allow an unambiguous phylogenetic placement. Concerning the size of the ungual phalanges, the feet of P. poliotauros correspond to those of extant hawks and allies (Accipitridae). We therefore hypothesize that it used its feet to dispatch prey items in a hawk-like manner, whereas extant owls kill prey with their beak. Primoptynx and protostrigid owls were possibly specialized in foraging on prey items that required an accipitrid-like killing strategy, such as larger-sized or more defensive mammals. The extinction of these peculiar owls may have been related to the radiation of accipitrid diurnal birds of prey, which appear to have diversified in the late Eocene and early Oligocene.

The preparietal, a neomorphic midline ossification on the skull roof, is thought to have evolved three times in therapsids, but its development and homology remain poorly understood. Here, we provide preliminary data on the histology of this element in specimens referred to Diictodon feliceps and an indeterminate species of Lystrosaurus. The preparietal has previously been noted to vary substantially in its shape on the dorsal surface of the skull in several dicynodonts, and we found similar variation in thin section. In Diictodon, the preparietal forms a prong that embeds itself entirely within the frontals and shows evidence of a midline suture anteriorly. The sectioned specimen of Lystrosaurus shows histological evidence of immaturity and features a well-defined midline suture at the posterior end of the preparietal, although an anterior prong was not present. In both taxa, the anteroventral portion of the preparietal forms a strongly interdigitating suture with the underlying frontals and parietals. More posteriorly, the preparietal is composed of fibrolamellar bone suggestive of rapid posteroventral growth. In large dicynodont species, the dorsal expression of the preparietal appears to show negative allometry compared with other cranial roofing elements during ontogeny, but the significance of this geometry is unclear. In addition, histological work is needed on the preparietal in gorgonopsians and biarmosuchians to determine whether the features characterizing dicynodonts are also seen in the other two groups of therapsids that evolved a preparietal. The therapsid preparietal provides a rare opportunity to study the development and evolution of a neomorphic cranial element in the vertebrate fossil record.

The Kibenikhoria and Ernestokokenia local faunas were described in the 1930s by George G. Simpson, who defined them as two chronologically consecutive faunas based on a comparison with the Casamayoran South American Land Mammal Age (SALMA). Later, in the 1980s, the two faunas were respectively the basis of the Itaboraian and Riochican SALMAs, a scheme broadly accepted for more than eight decades. However, a systematic revision of their native ungulates is still lacking. In this contribution, we studied several collections performed in the classical localities of Cañadón Hondo and Bajo Palangana (southeastern South America) and discuss the systematic status of the mammals listed in their faunas. Our results allow us to (1) assert that the beds containing the mammal associations in Cañadón Hondo and Bajo Palangana are located in the upper Las Flores Formation and are essentially contemporaneous; (2) improve the knowledge for Kibenikhoria get and Henricosbornia lophodonta; (3) propose H. waitehor and ?Peripantostylops orehor to be synonymous with H. lophodonta; and (4) recognize Shecenia ctirneru, Seudenius cteronc, and ?Postpithecus as Trigonostylopidae aff. Trigonostylops. The Kibenikhoria and Ernestokokenia faunas have six genera in common; five of them are shared with the lower levels of the Sarmiento Formation. Kibenikhoria get, Isotemnus ctalego, Pliodolops winecage, and Gasternia ctalehor are exclusive taxa of the Kibenikhoria fauna. Here, the Riochican sensu stricto from Marshall is used to include both local faunas, which represents a distinct and more derived fauna than that from the Itaboraí Formation, but with a less advanced evolutionary stage than the lower Sarmiento Formation.

Three species of Deinotherium sensu stricto (Proboscidea, Deinotheriidae), i.e., excluding Prodeinotherium, generally considered to have nonoverlapping chronostratigraphic distributions, are currently recognized from the Miocene of Europe: Deinotherium levius (late Astaracian/Aragonian, MN7+8), Deinotherium giganteum (type species; Vallesian, MN9–MN10), and Deinotherium proavum (a senior synonym of Deinotherium gigantissimum; Turolian, MN11–MN13). Here we describe a sample of 26 cheek teeth from four roughly coeval localities of Ronda Oest de Sabadell (ROS), in the Vallès-Penedès Basin, northeastern Iberian Peninsula, dated to the latest Vallesian (∼9.4–9.1 Ma, MN10) on biostratigraphic grounds. The remains from ROS-D3 represent all the permanent upper and lower dentition and can be unambiguously assigned to D. proavum, the largest deinothere from Europe, based on their large size (well above the range of D. giganteum). Remains from the other localities (ROS-D2, ROS-D5, and ROS-D8) are smaller and generally overlap in size with both D. proavum and D. giganteum. However, an assignment to the former species is more likely given that these species are not known to co-occur and that their dental size ranges were already known to overlap partially. The remains of D. proavum from ROS represent the oldest record of this species, the occurrence of which in the late Vallesian had already been recorded in the slightly younger (∼9.1 Ma) locality of Sinap 49, Turkey. Given that D. proavum is recorded before the Vallesian/Turolian boundary, and that smaller individuals of this species overlap in size with D. giganteum from the Vallesian, caution is required when making biostratigraphic correlations based on late Miocene deinothere remains from Europe.

Caviomorphs, the ctenohystrican rodents endemic to the Neotropics, have a long evolutionary history during the Cenozoic, and is one of the more abundant mammalian groups with striking morphological disparity. Several living taxa have auditory regions adapted to hearing low-frequency sounds, yet almost nothing is known about the basicranium in fossil taxa. The octodontoid Prospaniomys priscus from the lower Miocene of Patagonia, Argentina, exhibits a skull with a curious combination of generalized dental characters and supposed derived tympanic cavity. Owing to the basal phylogenetic position of P. priscus, the study of its basicranium based on high resolution X-ray computed tomography represents an excellent opportunity to study an ancestral morphological pattern. Comparisons with living octodontoids permit the evaluation of the auditory region in an evolutionary context. Our results identified that at least since the early Miocene octodontoids, and certainly caviomorphs, have specializations to enhance low-frequency hearing: highly coiled cochlea, small secondary bony laminae, well-developed tympanic cavity, and reduced or absent stapedius muscle, characters that seem not to be directly related to the environment. Possible generalized or specialized states for the latter features are discussed. The significance of this work lies in the fact that it is the first detailed anatomical description of the auditory regions of a fossil caviomorph, providing a new framework with regards to this region of the skull.

We provide a new morphological description of the holotype and a previously undescribed large sample of the type species of the genus CopemysWood, 1936, Copemys loxodon (Cope, 1874a), a Miocene North American cricetid rodent occasionally treated as the ancestor of the non-arvicoline cricetids (i.e., neotomines, sigmodontines, and tylomyines). Dental, mandibular, and skull morphology is described from material recovered in a quarry in the vicinity of the type locality in the Española Valley of New Mexico, U.S.A. Copemys loxodon is a small, brachydont cricetid characterized by a mandible with a large mental foramen lateral in position and an enlarged retromolar fossa; the skull having wide infraorbital foraminae and robust zygomatic arches; and the upper molars being pentalophodont, the lower molars tetralophodont. The procingulum of the M1 has two conules, an enamel atoll is present on the M2, and the procingulum of m1 is composed exclusively of the lingual conulid. Preliminary comparisons among representatives of the 11 species of Copemys suggest that some forms currently recognized as Copemys probably do not belong to that genus, as indicated both by our results and those of other recent studies. Understanding the limits of variation in the type species of Copemys provides a starting point for the development of a more detailed phylogenetic analysis of early North American cricetids and their possible descendants.

During the 1980s, a Pliocene canid from Baja California Sur, Mexico, was described as a new Cerdocyon species, C. avius. Whereas some investigators believe that C. avius was related to the origin of South American foxes of the tribe Cerdocyonina, others suggested that it is related to members of the tribe Vulpini. Our observations and analyses confirm that it is a vulpine with a morphological combination of features that has not been described previously: marked subangular lobe in the hemimandible, m1 hypoconulid is practically absent, and the m3 is single-cusped. We propose Ferrucyon, gen. nov., as a genus including at present one species, F. avius. In the phylogenetic analysis, this species is related to North American Metalopex macconnelli, and to the Eurasian Nyctereutes spp., which creates a relationship between the foxes of the Old and New World.