Mammalian evolution and systematics

A new species of hipparionine horse, Hippotherium malpassii, is described from the MN13 interval from localities of the Baccinello V3 area (Italy). This species exhibits some advanced features of the facial region and cheek tooth dentition while other skull features and the postcranial skeleton are plesiomorphic. Research related to paleodiet suggests that Hippotherium malpassii was a mixed feeder, not as committed to grass feeding as many Central European species of Hippotherium. However, it may be considered as being similar to others such as Hippotherium primigenium from Eppelsheim (Germany) and Hippotherium microdon from Baltavar (Hungary). Studies of carbon and oxygen isotopes suggest that Hippotherium malpassii from the Baccinello V3 area lived in a forested context and it is inferred herein that it likely ate grass of relatively low abrasive character. Regarding the paleogeography of the species, Hippotherium originated in Central Europe early on in the MN9 interval (ca. 11 Ma) and underwent a modest evolutionary radiation there during the Vallesian and early Turolian (MN9-11). It is documented as having then dispersed throughout the Balkans into Greece during MN11/12 where it is represented by Hippotherium brachypus from the locality of Pikermi (Greece). During the interval MN12, the range of Hippotherium brachypus was extended and populations of very large size with massive metapodials evolved throughout this period. Hippotherium is not documented from the Baccinello area in Tuscany until the base of the MN13 interval (Baccinello V3 faunas) and may have immigrated from the Pannonian Basin, Hungary. The genus Hippotherium would appear to have become extinct at the end of MN12, the latter considered as being a result of increased continental drying and reduction of forest and woodland habitat. Its occurrence at Baccinello V3 in the MN 13 interval represents the latest occurrence of the genus in Europe.

The terrestrial mammal diversity recovered from levels of Banco Negro Inferior (Lower Black Bank) at Punta Peligro and surrounding areas, in southeastern Chubut Province (Argentina) is detailed. Most of the metatherian taxa here described are new for this mammalian assemblage, which in turn is the base of the late Danian (early Paleocene, Peligran Land-mammal-age). Differences between this association and that of Tiupampa, in Bolivia (also of Paleocene age) are remarkable. The former represent a mixture of Gondwanan and Holarctic lineages: monotremes, gondwanatherians, dryolestoids, metatherians, and eutherians, while those of Tiupampa are strictly therian in nature and with Laurasic affinities. More important than the differences in age between these faunas, we infer a decisive biogeographic influence in the composition of each one of them: the Punta Peligro fauna would be part of an Andean Region (Austral Kingdom) radiation, while that of Tiupampa seems to be more typically Neotropical (Holotropical Kingdom). Metatherians and eutherians from Punta Peligro are more derived than those of Tiupampa, and anticipate several lineages recorded in Eocene levels at other South American localities. The updated list of mammals from the Banco Negro Inferior includes the following taxa: Prototheria, Monotremata, Ornithorhynchidae: Monotrematum sudamericanum; Allotheria, Gondwanatheria, Sudamericidae: Sudamerica ameghinoi; Cladotheria, Dryolestoidea Peligrotheriidae: Peligrotherium tropicalis; Metatheria, "Ameridelphia", Derorhynchidae: Derorhynchus aff. D. minutus; family indet.: Didelphopsis primaeva sp. nov.; Polydolopimorphia, Bonapartheriidae: Salamancatherium lacerum gen. et sp. nov.; family indet. Alfredocarlinia cratera gen. et sp. nov.; and eventually ?Sparassodonta, family, genus and species indet.Metatheria, order, family, genus and species indet.; Eutheria, Panperissodactyla, Litopterna, Notonychopidae: Requisia vidmari; Didolodontidae: Raulvaccia peligrensis, Escribania chubutensis, E. talonicuspis. Keywords. Mammalia, Danian, early Paleocene, Patagonia, Punta Peligro

The terrestrial mammal diversity recovered from levels of Banco Negro Inferior (Lower Black Bank) at Punta Peligro and surrounding areas, in southeastern Chubut Province (Argentina) is detailed. Most of the metatherian taxa here described are new for this mammalian assemblage, which in turn is the base of the late Danian (early Paleocene, Peligran Land-mammal-age). Differences between this association and that of Tiupampa, in Bolivia (also of Paleocene age) are remarkable. The former represent a mixture of Gondwanan and Holarctic lineages: monotremes, gondwanatherians, dryolestoids, metatherians, and eutherians, while those of Tiupampa are strictly therian in nature and with Laurasic
affinities. More important than the differences in age between these faunas, we infer a decisive biogeographic influence in the composition of each one of them: the Punta Peligro fauna would be
part of an Andean Region (Austral Kingdom) radiation, while that of Tiupampa seems to be more typically Neotropical (Holotropical Kingdom). Metatherians and eutherians from Punta Peligro are more derived than those of Tiupampa, and anticipate several lineages recorded in Eocene levels at other South American localities. The updated list of mammals from the Banco Negro Inferior includes the following taxa: Prototheria, Monotremata, Ornithorhynchidae: Monotrematum sudamericanum;
Allotheria, Gondwanatheria, Sudamericidae: Sudamerica ameghinoi; Cladotheria, Dryolestoidea, Peligrotheriidae: Peligrotherium tropicalis; Metatheria, "Ameridelphia", Derorhynchidae: Derorhynchus
aff. D. minutus; family indet.: Didelphopsis primaeva sp. nov.; Polydolopimorphia, Bonapartheriidae: Salamancatherium lacerum gen. et sp. nov.; family indet. Alfredocarlinia cratera gen. et sp. nov.; and eventually ?Sparassodonta, family, genus and species indet.Metatheria, order, family, genus and species indet.; Eutheria, Panperissodactyla, Litopterna, Notonychopidae: Requisia vidmari; Didolodontidae: Raulvaccia peligrensis, Escribania chubutensis, E. talonicuspis.
Keywords. Mammalia, Danian, early Paleocene, Patagonia, Punta Peligro.

The zygoma, or jugum, is a cranial element that was present in Mesozoic tetrapods, well before the appearance of mammals. Although as an entity the zygoma is a primitive retention among mammals, it has assumed myriad configurations as this group diversified. As the zygoma is located at the intersection of the visual, respiratory, and masticatory apparatuses, it is potentially of great importance in systematic, phyloge-netic, and functional studies focused on this region. For example, the facial component of the zygoma and its contribution to a postorbital bar (POB) appear to be relevant to the systematics of a number of mammali-an subclades, and the formation of a bony postorbital septum (POS) that separates the orbit from the infratemporal fossa is unique to, and thus potentially phylogenetically significant for uniting anthropoid primates, while the zygoma itself appears to serve to resist tension and bending forces during mastication. In order to better understand the zygoma in the context of its contributions to the circumorbital region, we documented its morphological expression in specimens representing 10 orders of mammals. Since the presence of a POB and of a POS has long been used to justify uniting extant primates and anthropoid primates as respective clades, and because postorbital closure (POC) is morphologically more complex than a POB, we provide detail necessary to address these claims. Our taxically broad overview also allowed us to provide for the first time definitions of configurations that can be applied to future studies. Using a different, but also taxically broad sample of mammals, and of primates in particular, we performed two geometric morphometric

The shape and arrangement of cusps and crests and the orientation of wear striations on the cheek teeth of fossil mammals can be used to reconstruct occlusal patterns. Occlusal patterns have been documented previously in a variety of therian mammals and also in triconodonts and docodonts among nontherians. This is the first detailed analysis of patterns of jaw movement and dental function in a member of the highly specialized nontherian order Multituberculata (Allotheria). Ptilodus, a Paleocene multituberculate, appears to have had two cycles of mastication that followed different paths of movement and utilized different sets of teeth. The first cycle, the slicing-crushing cycle, occurred as the large, laterally-compressed fourth lower premolar (P4) sliced orthally into food items held primarily against the fourth upper premolar (P4). Food items sliced in this manner passed down both the labial and lingual sides of P4, forming subparallel striations in valleys between the nearly vertical enamel ridges. The second cycle is the grinding cycle in which the mandible was retracted while the molars were in tight occlusion, thus producing longitudinal striations on the molars. Unlike the pattern in therians, tricon- odonts, and docodonts, there is no transversely triangular masticatory orbit in the grinding cycle of multituberculates. The generally accepted idea that the labial aspect of P4 in ptilodontoid multituber- culates sheared orthally against the lingual aspect of P4 is not supported. Instead, predominantly hori- zontal striations developed on the posterolabial wear facet of P4, and on a conjoined facet posterolingually on P4 and anterolingually on the first upper molar (M1), indicate that relative movement between these surfaces was largely palinal (i.e., the jaw moved from front to back), rather than orthal and occurred during the grinding cycle of mastication. In considering the dietary preferences of ptilodontoid multituberculates, it appears that most members were not folivorous. The small size of many species of Ptilodontoidea suggests that they could not have subsisted on a folivorous diet, which is rich in structural carbohydrates. The length of striations on the sides of P4 of Ptilodus, one of the largest of the Ptilodontoidea, indicates that large, hard food items were ingested. The presence of both smooth and highly-striated enamel on homologous dental wear facets in different individuals of Ptilodus mediaevus from a single quarry sample suggests a varied diet. The recent suggestion that ptilodontoids were omnivorous is supported

A new species of hipparionine horse, Hippotherium malpassii, is described from the MN13 interval from localities of the Baccinello V3 area (Italy). This species exhibits some advanced features of the facial region and cheek tooth dentition while other skull features and the postcranial skeleton are plesiomorphic. Research related to paleodiet suggests that Hippotherium malpassii was a mixed feeder, not as committed to grass feeding as many Central European species of Hippotherium. However, it may be considered as being similar to others such as Hippotherium primigenium from Eppelsheim (Germany) and Hippotherium microdon from Baltavar (Hungary). Studies of carbon and oxygen isotopes suggest that Hippotherium malpassii from the Baccinello V3 area lived in a forested context and it is inferred herein that it likely ate grass of relatively low abrasive character. Regarding the paleogeography of the species, Hippotherium originated in Central Europe early on in the MN9 interval (ca. 11 M...

The Pecorans (higher ruminants) are believed to have rapidly speciated in the Mid-Eocene, resulting in five distinct extant families: Antilocapridae, Giraffidae, Moschidae, Cervidae, and Bo-vidae. Due to the rapid radiation, the Pecoran phylogeny has proven difficult to resolve, and 11 of the 15 possible rooted phylogenies describing ancestral relationships among the Antilo-capridae, Giraffidae, Cervidae, and Bovidae have each been argued as representations of the true phylogeny. Here we demonstrate that a genome-wide single nucleotide polymorphism (SNP) geno-typing platform designed for one species can be used to genotype ancient DNA from an extinct species and DNA from species diverged up to 29 million years ago and that the produced genotypes can be used to resolve the phylogeny for this rapidly radiated infraorder. We used a high-throughput assay with 54,693 SNP loci developed for Bos taurus taurus to rapidly genotype 678 individuals representing 61 Pecoran species. We produced a highly resolved phylogeny for this diverse group based upon 40,843 genome-wide SNP, which is five times as many informative characters as have previously been analyzed. We also establish a method to amplify and screen genomic information from extinct species, and place Bison priscus within the Bovidae. The quality of genotype calls and the placement of samples within a well-supported phylogeny may provide an important test for validating the fidelity and integrity of ancient samples. Finally, we constructed a phylogenomic network to accurately describe the relationships between 48 cattle breeds and facilitate inferences concerning the history of domestication and breed formation. ancient DNA Pecorans domestication

The Pecorans (higher ruminants) are believed to have rapidly speciated in the Mid-Eocene, resulting in five distinct extant families: Antilocapridae, Giraffidae, Moschidae, Cervidae, and Bovidae. Due to the rapid radiation, the Pecoran phylogeny has proven difficult to resolve, and 11 of the 15 possible rooted phylogenies describing ancestral relationships among the Antilocapridae, Giraffidae, Cervidae, and Bovidae have each been argued as representations of the true phylogeny. Here we demonstrate that a genome-wide single nucleotide polymorphism (SNP) genotyping platform designed for one species can be used to genotype ancient DNA from an extinct species and DNA from species diverged up to 29 million years ago and that the produced genotypes can be used to resolve the phylogeny for this rapidly radiated infraorder. We used a high-throughput assay with 54,693 SNP loci developed for Bos taurus taurus to rapidly genotype 678 individuals representing 61 Pecoran species. We produced a h...

The zygoma, or jugum, is a cranial element that was present in Mesozoic tetrapods, well before the appearance of mammals. Although as an entity the zygoma is a primitive retention among mammals, it has assumed myriad configurations as this group diversified. As the zygoma is located at the intersection of the visual, respiratory, and masticatory apparatuses, it is potentially of great importance in systematic, phylogenetic, and functional studies focused on this region. For example, the facial component of the zygoma and its contribution to a postorbital bar (POB) appear to be relevant to the systematics of a number of mammalian subclades, and the formation of a bony postorbital septum (POS) that separates the orbit from the infratemporal fossa is unique to, and thus potentially phylogenetically significant for uniting anthropoid primates, while the zygoma itself appears to serve to resist tension and bending forces during mastication. In order to better understand the zygoma in the...