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A new genus of ‘actinolepid’ arthrodire placoderm, Erikaspis, is named to contain “Kujdanowiaspis” zychiStensiö, 1945, from the Lochkovian–Pragian deposits (Lower Devonian) of Podolia (Ukraine). This new genus occurs together with the genus KujdanowiaspisStensiö, 1942, to which its type species was previously assigned. Distinctive ornamentation and pattern of dermal plates justify this new assignment. A phylogenetic analysis places Erikaspis, gen. nov., as a close relative of Kujdanowiaspis and of the contemporaneous species Sigaspis lepidophoraGoujet, 1973, from Spitsbergen, all of them belonging to the family Kujdanowiaspididae Berg, 1955.
Three specimens of a fossil catfish, collected from the Upper Miocene of Toros-Menalla (Western Djurab, Chad), are identified as members of Auchenoglanis (Claroteidae, Auchenoglanidinae) based on the shape and the ornamentation of the bones of the skull, including a markedly developed parieto-supraoccipital broadly connected with the first nuchal plate. The description is based on a comparison with living specimens of the two valid species of the genus, providing details on their bony anatomy. The fossil fish is a new species, Auchenoglanis soye sp. nov. Original features include supraoccipital process more than twice as wide as long, straight posterolateral border of the sphenotic, parurohyal with a median anterior process, and lateral articular surfaces of the second dorsal spine lateral to the foramen. Auchenoglanis fish are known since the Late Miocene and are endemic to the Nilo-Sudanese province. The fossil record was previously limited to a few isolated spines identified as Auchenoglanis sp., and A. soye sp. nov. is the first fossil species described for the genus. On the basis of preliminary observations of the ichthyofauna from Toros-Menalla, the scarcity of Auchenoglanis in the fossil record might be due to the low abundance of a fish with a rather high ecological valence.
New material of the Australian Lower Carboniferous rhizodontid Barameda provides additional information on poorly known aspects of rhizodontid anatomy, including the braincase and branchial arches, and indicates that two species of Barameda are present in the Mansfield Group, a larger poorly ossified species, B. decipiens, and a new species, Barameda mitchelli n. sp. based on the smaller well ossified specimens previously assigned to B. decipiens. Unusually, in a new pectoral fin specimen assigned to B. decipiens, the humerus lacks ossified entepicondylar and pectoral processes, strong projections present on the humeri of most sarcopterygian fish and tetrapods. Juveniles of rhizodontids and of Eusthenopteron (Tristichopteridae) also lack these processes (ossifying later in development), which along with poor overall ossification of the fin in juveniles and in B. decipiens, indicates that the pectoral fin of the latter has been affected by heterochronic processes. These observations suggest a degree of developmental variability (timing, degree of ossification) in the entepicondyle relative to the rest of the humerus, which could be extended to other posterior processes of pectoral fin elements such as the ulnare flange. This flange is present in tristichopterids but absent in rhizodontids and taxa closely related to the origin of tetrapods, such as Panderichthys.
The fossil vertebrate localities near Humboldt, Richardson County, Nebraska, have produced a diverse assemblage of amphibians from near the Permo-Carboniferous (C-P) boundary, including at least one species of dissorophoid (described here), a trimerorhachid, juvenile and adult specimens of the dvinosaur Acroplous vorax, gymnarthrid microsaur material, numerous skeletons, skulls, and isolated vertebrae assignable to two species of the lysorophian Brachydectes, and diadectid teeth. A new genus and species of amphibamid dissorophoid, Plemmyradytes shintoni, is described from the lower half of the Permian-aged Eskridge Formation (early Asselian) near Humboldt. P. shintoni is only the second amphibamid species described from the Permo-Carboniferous midcontinent sequence in the Kansas-Nebraska region. Among amphibamids, it is set apart by the following suite of characters: (1) reduction of the lateral exposure of the palatine, (2) a long, narrow supratemporal (at least twice as long as broad) roofing the otic notch, (3) a posteriorly elongated squamosal, (4) long anterior maxillary teeth, decreasing in size posteriorly, (5) a shallow dentary with a long lateral dentary trough, and (6) dentary teeth that are slightly smaller than the maxillary teeth (approximately one-half to two-thirds as long). A cladistic analysis of 67 dissorophoid characters from 17 taxa supports a clade uniting P. shintoni with ‘Tersomius’ sp. and Micropholis stowi within a monophyletic Amphibamidae. The demonstration of evolutionary trends within the family based on the new data allows a comparison of competing phylogenetic hypotheses.
Thaumastosaurus gezei, sp. nov., is described based on the incomplete, holotype skull and an isolated, referred squamosal, both from the so-called “old collections” (late middle or late Eocene in age) from the Phosphorites du Quercy, France. A suite of cranial features, mainly involving sculpture patterns and details of the maxilla and squamosal, differentiates T. gezei from the other three species of Thaumastosaurus. T. gezei appears to be unique among known species of Thaumastosaurus and is unusual among other anurans in having an anteriorly elongate process of the squamosal that extends along the entire dorsal edge of the maxilla, thereby preventing the maxilla from contacting the nasal and contributing to the orbital margin. This derived squamosal configuration, and some other cranial features, suggest a possible relationship between Thaumastosaurus and the South American ceratophryids. If such a relationship proves correct, Thaumastosaurus would be one of the few vertebrate taxa from the Eocene of Europe with South American affinities.
The holotype of Sauropareion anoplus, a procolophonoid reptile from the Lystrosaurus Assemblage Zone of the Beaufort Group, lowermost Triassic of South Africa, is described in detail. New information includes the presence of fields of teeth on the vomer, the palatine, and the pterygoid, and the presence of a relatively long, tear-shaped interpterygoid vacuity. The parabasisphenoid features relatively broad posterolateral wings. A cleithrum is present. An entepicondylar foramen is present, but neither an ectepicondylar foramen nor a supinator process are present. We coded Sauropareion for the data matrices in two recent studies that had excluded this genus from consideration in phylogenetic analyses. Running of these slightly augmented matrices results in numerous optimal trees (8 and 15 optimal trees), i.e. the inclusion of Sauropareion greatly weakens the resolution of the tree topologies; in one case the inclusion of Sauropareion highlights the lack of anatomical information available for most procolophonids, and in the other it reveals weaknesses that are possibly attributable to character selection. We conducted a new phylogenetic analysis of Procolophonoidea, incorporating new phylogenetic characters from other studies. Our results confirm the position of S. anoplus as the sister taxon of a clade comprising all procolophonoids exclusive of Coletta seca. New phylogenetic definitions are devised for Owenettidae and Procolophonidae, making the latter one of the two primary clades within Procolophonoidea; Owenettidae and Procolophonidae are now sister taxa. As a result, the non-owenettid procolophonoids species S. anoplus and C. seca can be recognized as the most basal members of Procolophonidae.
The sequence of neurocentral suture closure is one criterion for the determination of ontogenetic stage in extant crocodylians. This pattern is frequently used to assess ontogeny for a variety of fossil archosaurs that may or may not follow the same sequence and timing of suture closure. Phytosaurs are one of the few basal archosaur groups with a sample size large enough to help test whether the crocodylian pattern of suture closure is plesiomorphic for Pseudosuchia and Archosauria. Analysis of a large sample of North American phytosaur specimens confirms that phytosaurs share the crocodylian state of closure, and so this pattern is probably plesiomorphic for the Pseudosuchia. An additional independent ontogenetic trend observed in phytosaurs is that the lateral fossae on cervical vertebrae in phytosaurs deepen with ontogeny. A preliminary survey indicates that there is considerable variation of both the sequence and timing of neurocentral suture closure in other archosaur clades. Therefore, it is unwise to apply a priori the crocodylian pattern to other archosaur groups to determine ontogenetic stage. Currently, apart from histological data, there are few if any reliable independent criteria for determining ontogenetic stage. I propose that histology be integrated with independent ontogenetic criteria (such as neurocentral suture closure) and morphometric data to provide a better understanding of archosaur ontogeny.
Two exquisitely preserved specimens from the Late Cretaceous of southeastern France, together with less complete material from southwestern France, allow the most complete description of the cranial morphology of Acynodon iberoccitanus. The extremely brevirostrine condition associated with a unique dentition might indicate derived dietary behavior for Acynodon. New characters were coded in a previously published matrix. In this context, Acynodon is placed in a polytomy at the base of Globidonta. As an early European form, the position of Acynodon implies that no biogeographic models can be favoured to explain alligatoroid and globidontan migrations between North America and Europe.
The first detailed description of the lambeosaurine Lambeosaurus magnicristatus (Ornithischia: Hadrosauridae) confirms that it is a distinct taxon characterized by its comparatively enormous cranial crest, formed predominantly by the caudodorsal process of the premaxilla, and an acute crest-snout angle. The holotype of L. magnicristatus occurs stratigraphically higher than all other Dinosaur Park Formation lambeosaurines at the Dinosaur Provincial Park locality. The only referred specimen was collected over 170 kilometers southeast of the type locality. Correlation of its host stratum with the well-known Dinosaur Park section reveals that L. magnicristatus has no biostratigraphic overlap with L. lambei and suggests that it replaces L. lambei on a regional scale in southern Alberta at the end of ‘Dinosaur Park time.’ Species-level phylogenetic analysis of Lambeosaurinae corroborates the monophyly of Lambeosaurus. The genus is characterized by five apomorphies, including a procumbent crest, complete enclosure of the ophthalmic canal of the laterosphenoid, the presence of a flange on the caudodorsal process of the premaxilla that overlaps the nasal in the rostral region of the crest, caudal extension of the premaxilla such that it forms the caudal margin of the crest, and a unique joint between the rostral nasal and the caudodorsal process of the premaxilla. Lambeosaurine phylogeny indicates that the development of a hypertrophied cranial crest evolved independently at least three times within the clade, suggesting that the crest enlargement is a recurring evolutionary trend within Lambeosaurinae.
Almost 70 years after their discovery, more than 450 isolated avian bones from the Paleocene fissure filling of Walbeck are described. Fissuravis weigelti gen. et sp. nov. is represented by a coracoid with a very large cotyla scapularis and short processus acrocoracoideus and tentatively assigned to the palaeognathous Lithornithidae. Another coracoid of a large flightless bird, misidentified as a mammalian scapula before, is assigned to the Gastornithidae and is the earliest fossil record of this taxon. Most other bird bones from Walbeck belong to Walbeckornis creber gen. et sp. nov., which is represented by all major limb elements; this species resembles charadriiform birds and the ‘gruiform’ Messel-ornithidae, but its plesiomorphic morphology in combination with the poorly resolved higher level phylogeny of extant birds does not allow a definitive phylogenetic assignment. Several coracoids, humeri, and tarsometatarsi are assigned to Gradiornis walbeckensis gen. et sp. nov., which resembles some species of the Cariamae in overall morphology. A tarsometatarsus and a tentatively referred praemaxilla of the strigiform Berruornis are described as a new species, B. halbedeli. A few other unnamed taxa are represented by fragmentary remains. All of the sufficiently well-preserved avian taxa belong to terrestrial forms, and by its species poorness the Walbeck avifauna sharply contrasts with the very diverse avifaunas known from the earliest Eocene of Europe.
The anatomy of a new, enormous phorusrhacid (Aves: Cariamae) from the Middle Miocene Collón Curá Formation of northwestern Patagonia (Río Negro province, Argentina) is described. The new phorusrhacid is known by a single specimen that consists of a nearly complete skull associated with a tarsometatarsus and a pedal phalanx. The new fossil is the largest known phorusrhacid and its morphology resembles more that of taxa traditionally grouped within phorusrhacines. Its skull—by far the best preserved among large phorusrhacids—provides a great deal of previously unknown anatomical information and indicates that reconstructions of the skull of gigantic phorusrhacids based on their smaller relatives are unwarranted.
A new burnetiamorph therapsid, Lophorhinus willodenensis, gen. et sp. nov., is described on the basis of a partial skull from the Permian Teekloof Formation (Beaufort Group) of the Beaufort West District, Western Cape Province, South Africa. Although similar to the coeval burnetiamorph Lobalopex, Lophorhinus is autapomorphic in its possession of a semicircular median nasal crest formed by unfused nasals, doubled lacrimal foramina, an ossified sphenethmoid, and a mesiodistally compressed first premaxillary tooth. New morphological data provided by Lophorhinus permit the recognition of several character states that have been difficult to evaluate in other burnetiamorph taxa, including a (1) short dorsal process of the premaxilla, (2) contribution of the frontal to the upper orbital margin, and (3) lack of a significant contribution of the prefrontal to the supraorbital boss. An updated cladistic analysis of twelve biarmosuchians suggests that Lophorhinus is the sister taxon to Lobalopex Burnetiidae. However, the precise relationships among Lemurosaurus, Lobalopex, and Lophorhinus are unresolved in the strict consensus of 25 primary trees. The discovery of Lophorhinus in the Tropidostoma Assemblage Zone (AZ) demonstrates that multiple burnetiamorph taxa co-existed in southern Gondwana during Middle and Late Permian times. Systematic collecting from the Tropidostoma AZ suggests that carnivorous burnetiamorphs, gorgonopsians, and therocephalians are exceedingly rare components of the tetrapod fauna, with herbivorous dicynodonts dominating the fossil record (121/126 specimens collected). Field collections of tetrapods from the Tropidostoma AZ are most similar in their composition to those described from the stratigraphically higher Dicynodon AZ, implying relatively stable tetrapod community structure in southern Pangea for the final 10 million years of the Permian.
The theory that the reduced postdentary bones and quadrate of non-cyndonts were not only the morphological homologues, but also the functional equivalents of the mammalian tympanic bone and ear ossicles is tested on the basis of detailed new information of a specimen of Chiniquodon. The anatomy is shown to be a compromise between the respective requirements for a persistent, though reduced, stress transmission function of a jaw articulation, and an acoustic transformation function of a middle ear. There was a sound pressure level transformer ratio of about 30, but the mass and compliances of the elements restricted sensitivity to low frequencies, up to perhaps 2 kHz. Neither an air-filled tympanic cavity, nor a dedicated tympanic membrane were present, and snakes and other modern reptiles lacking a tympanic cavity offer a better mechanical analogy than mammals for the ear function of a cynodont. The fully mammalian acoustic transformer system, with tympanic cavity and tympanic membrane, could only have evolved after the origin of the dentary-squamosal jaw articulation, and was correlated with miniaturisation in the lineage leading to basal mammaliaforms.
A new specimen of Chaliminia musteloides Bonaparte is described from the upper section of the Los Colorados Formation (Late Carnian–Early Norian) of Argentina. A cladistic analysis of ictidosaurians supports its monophyly. Chaliminia and Elliotherium, grouped in the new subfamily Chalimininae, were placed as sister taxa to the new subfamily Pachygenelinae, which includes Pachygenelus, Diarthrognathus, and Tritheledon. Irajatherium is basal to both subfamilies as a stem Tritheledontidae. Riograndia represents the most basal non-tritheledontid ictidosaurian. The resulting tree topology agrees with the age of the fossil record of each ictidosaurian species. Although our analysis does not test the relationship of ictidosaurians with regard to Mammaliaformes, it is clear from our tree that ictidosaurians are closely related to them. Several derived characters seem to have been acquired convergently in both lineages and relate to food processing, development of primary chewing musculature and ancillary structures. In other aspects, ictidosaurians remained very conservative, or reverted to ancestral morphologies, such as the presence of interpterygoidal-vacuities. Analysis of the vacuities indicates that they represent an ancestral condition that facilitated the development of the mammalian skull base constituted by the reduced pterygoids, the basisphenoid, and posteriorly the development of the presphenoid by the ventral extension of the braincase. Possibly, the main factors in the remodeling of this area are the development of the sphenoid sinus and the forward and ventral expansion of the cranial cavity. The re-acquisition of interpterygoid vacuities among ictidosaurians could be the result of a paedomorphic (neotenic or progenetic) alteration of the developmental pattern.
The locality of Thermopigi in northern Greece has yielded a well-preserved skull of Ancylotherium pentelicum, among a rich collection of late Miocene mammals. It is the most complete Ancylotherium skull ever reported, and lack of crushing makes it especially valuable. Its most remarkable feature is the inflation of the frontal bone, which is strongly reminiscent of the dome of the North American TylocephalonyxCoombs, 1979, although the degree of inflation is weaker than in that genus. An analysis of some characters found in the Miocene Schizotheriinae leads to the conclusion that Ancylotherium is more likely to be closely related to other Eurasian and African members of this subfamily than to Tylocephalonyx, and that the domes evolved in parallel.
A relatively complete skull of Parelasmotherium, a giant elasmotherine rhinocerotid with a huge nasal horn, is described from an early late Miocene locality of the Linxia Basin in Gansu, China. Comparing the new cranial material of Parelasmotherium, we confirm that Ningxiatherium belongs to a valid and independent genus. New knowledge concerning the cranial and dental morphology of Parelasmotherium allows insight into the phylogenetic position of this genus among elasmotheres. A sister-group relationship between Parelasmotherium and Ningxiatherium is proposed on the basis of cranial and dental evidence. Shared derived characters that support this relationship include: anterior rims of orbit far behind the level of M3; raised lower rim of orbit; long, wide, fused nasal bones that angle ventrally; a retracted nasal notch at the level of the P4/M1 boundary; broadly separated parietal crests; tooth rows restricted to the anterior half of skull; extremely expanded hypocones of molars; very narrow metalophs; and a lingually elongated protoloph of M3. Parelasmotherium was obviously a grazer, as shown by the high crown, strong wear, massive cement, and wrinkled enamel on its teeth. The coexistence of Parelasmotherium and Ningxiatherium in the Linxia Basin indicates that the ecological differentiation occurred during the early late Miocene. The two genera occupied different ecological niches with distinct diets, grazing grasses for Parelasmotherium and browsing leaves for Ningxiatherium.
The record of Neogene faunas from the northeast of Argentina (Mesopotamia) is sporadic, whereas the late Miocene vertebrate-bearing horizons in this area contain a very abundant and diverse fauna, the Pliocene deposits are poorly known and have been unfossiliferous until now. This situation makes the understanding of the biogeographic and evolutionary history of the Mesopotamian taxa difficult. In this contribution, the first mammals are described that were recovered from the most basal levels of the Punta Gorda Group ( = Alvear Formation) at Entre Ríos Province, assigned to the late Pliocene (Lower Matuyama) by previous paleomagnetic studies. These beds are paleomagnetically bracketed between 1.95 and 2.6 Ma (late Pliocene) in the Alvear section and help to refine the biostratigraphy of these species elsewhere in northeastern Argentina. The echimyids Paramyocastor diligens (Ameghino, 1888) and Eumysops sp., and the hegetotheriid Paedotherium cf. typicum herein reported support a Pliocene age for the sediments from which they were recovered. These mammals suggest a paleoenvironment characterized by semiarid and open lowlands, markedly different than that inferred for the Late Miocene in this area.
A fossil pangolin is described from the early Pliocene of Langebaanweg, South Africa. Morphological adaptations indicate that the specimen was not arboreal as are the living African species Manis tricuspis and M. tetradactyla, but was probably ground dwelling and may have engaged in a quadrupedal gait similar to that of the living representatives of the African species, Manis gigantea. In addition, it may have used its forelimbs for more extensive digging than does the living African Manis temminckii. The tail length, limb bone widths and proportions, and humeral morphology support the assignment of this specimen to Manis gigantea, making it the oldest known fossil representative of this species and the only confirmed fossil pangolin from South Africa.
The Nelson Bay Local Fauna, recovered from a paleosol horizon exposed in the sea cliffs at Nelson Bay, Portland, Victoria, Australia, comprises over 30 different mammalian species making it one of the most diverse early Pleistocene faunas in Australia. Its age is well constrained to 1.77–0.78 Ma by radiometric, biostratigraphic and paleomagnetic dating methods. The composition of the fauna, which includes predominantly browsing-grade taxa and a number of arboreal species, suggests the paleoenvironment was a mosaic of open forest and woodland. This habitat acted as a refuge for forest-adapted taxa previously known only from the early Pliocene, such as the ektopodontid, Darcius duggani, the giant ring-tailed possum, Pseudokoala, a small palorchestid, Palorchestes pickeringi, and a new species of Protemnodon. The Nelson Bay Local Fauna was compared at the generic level with six other faunas ranging in age from early Pliocene to Recent using Simpson's coefficient of faunal resemblance. This analysis shows the Nelson Bay Local Fauna, with its combination of extant, typical Pleistocene megafauna, and ‘relict’ Pliocene species, to be unusual in the region. The combination of taxa in the Nelson Bay Local Fauna may be characteristic of early Pleistocene terrestrial mammal assemblages of southeastern Australia, and could be used cautiously to date other faunas, e.g., Childers Cove Local Fauna.
A complete skull of a fossil tapir (Perissodactyla: Tapiridae) was recovered from outcrops of the Arroyo Feliciano Formation (Late Pleistocene; Lujanian Age) in the Argentine Mesopotamia and is here recognized as a new species. The phylogenetic relationships of this new taxon, Tapirus mesopotamicus sp. nov., are revealed by cladistic character analysis using several extinct and extant taxa. The taxa included in the analysis are the extinct genera Miotapirus, Paratapirus, and Plesiotapirus, five North American paleospecies Tapirus veroensis, T. haysii, T. johnsoni, T. webbi, and T. polkensis, and all the living species of the genus Tapirus (T terrestris, T. pinchaque, T. bairdii, and T. indicus). Tapirus mesopotamicus sp. nov is diagnosed by having a robust and long skull with short rostrum relative to total length of cranium, a single and not arched sagittal crest, broad table of frontals on the anterior skull roof, temporal crests converging very near the frontal-parietal suture, palate very arched, premaxilla deeply notched above canine, maxilla and base of zygomatic process strikingly robust, P1 short and quadrangular, and mandibular condyle slender with posterior wall flat or somewhat concave. The resulting cladogram depicts a well-supported clade comprising the South American tapirs. The new taxon T. mesopotamicus sp. nov. groups with its sister taxon T. pinchaque, and together with T. terrestris, form a sister clade to T. bairdii and three North American fossil tapirs.
Gondwanatherians are a distinctive Cretaceous radiation of Gondwanan mammals. Fieldwork in the intertrappean beds of Karnataka and Andhra Pradesh, India has yielded a substantial collection of Maastrichtian mammals, including nine isolated teeth that represent at least two sudamericid gondwanatherians. We name a new taxon, Dakshina jederi, to which we refer six of the specimens and a previously unnamed form (VPL/JU/NKIM/25). The remaining specimens are identified as Gondwanatheria indeterminate. India's Late Cretaceous mammal fauna includes eutherians, a haramiyidan, and sudamericids. Whereas the eutherians likely represent a dispersal event from Laurasia and the haramiyidan represents a relictual distribution on Gondwana, the gondwanatherians are members of an endemic Gondwanan radiation. The sudamericid Dakshina possesses several derived features that suggest phylogenetic affinities with Lavanify from the Maastrichtian of Madagascar and to a lesser extent with Sudamerica from the Paleocene of Argentina. This pattern of phylogenetic relationships agrees with paleogeographic reconstructions for the breakup of Gondwana that hypothesize close biogeographic ties among India, Madagascar, and South America; however, gaps in our temporal and geographic sampling limit our understanding of biogeographic ties that India shares with Africa, Antarctica, and Australia.