A new family of diprotodontian marsupials from the latest Oligocene of Australia and the evolution of wombats, koalas, and their relatives (Vombatiformes)

We describe the partial cranium and skeleton of a new diprotodontian marsupial from the late Oligocene (~26–25 Ma) Namba Formation of South Australia. This is one of the oldest Australian marsupial fossils known from an associated skeleton and it reveals previously unsuspected morphological diversity within Vombatiformes, the clade that includes wombats (Vombatidae), koalas (Phascolarctidae) and several extinct families. Several aspects of the skull and teeth of the new taxon, which we refer to a new family, are intermediate between members of the fossil family Wynyardiidae and wombats. Its postcranial skeleton exhibits features associated with scratch-digging, but it is unlikely to have been a true burrower. Body mass estimates based on postcranial dimensions range between 143 and 171 kg, suggesting that it was ~5 times larger than living wombats. Phylogenetic analysis based on 79 craniodental and 20 postcranial characters places the new taxon as sister to vombatids, with which it forms the superfamily Vombatoidea as defined here. It suggests that the highly derived vombatids evolved from wynyardiid-like ancestors, and that scratch-digging adaptations evolved in vombatoids prior to the appearance of the ever-growing (hypselodont) molars that are a characteristic feature of all post-Miocene vombatids. Ancestral state reconstructions on our preferred phylogeny suggest that bunolophodont molars are plesiomorphic for vombatiforms, with full lophodonty (characteristic of diprotodontoids) evolving from a selenodont morphology that was retained by phascolarctids and ilariids, and wynyardiids and vombatoids retaining an intermediate selenolophodont condition. There appear to have been at least six independent acquisitions of very large (>100 kg) body size within Vombatiformes, several having already occurred by the late Oligocene

Body Shape and Life Style of the Extinct Balearic Dormouse Hypnomys (Rodentia, Gliridae): New Evidence from the Study of Associated Skeletons

Hypnomys is a genus of Gliridae (Rodentia) that occurred in the Balearic Islands until Late Holocene. Recent finding of a complete skeleton of the chronospecies H. morpheus (Late Pleistocene-Early Holocene) and two articulated skeletons of H. cf. onicensis (Late Pliocene) allowed the inference of body size and the calculation of several postcranial indexes. We also performed a Factorial Discriminant Analysis (FDA) in order to evaluate locomotory behaviour and body shape of the taxa. Using allometric models based on skull and tooth measurements, we calculated a body weight between 173 and 284 g for H. morpheus, and direct measurements of articulated skeletons yielded a Head and Body Length (HBL) of 179 mm and a Total Body Length of 295 mm for this species. In addition to the generally higher robustness of postcranial bones already recorded by previous authors, H. morpheus, similar to Canariomys tamarani, another extinct island species, displayed elongated zygopodium bones of the limbs and a wider distal humerus and femur than in an extant related taxon, Eliomys quercinus. Indexes indicated that Hypnomys was more terrestrial and had greater fossorial abilities than E. quercinus. This was also corroborated by a Discriminant Analysis, although no clear additional inference of locomotory abilities could be calculated

Early adaptive radiations of Aplodontoidea (Rodentia, Mammalia) on the Holarctic region: systematics, and phylogenetic and paleobiogeographic implications

International audienceThe Aplodontoidea, now restricted to only oneNorth American species (Aplodontia rufa), have shown awide Holarctic extension since the Upper Eocene. As theirfossil record is poor, their phylogenetic relationships andthe origins of their successive radiations remain unclear.We perform here phylogenetic analyses, primarily based ondental evidence (94 dental of 97 characters), restricted toPaleogene and early Miocene taxa (46 taxa) in order toavoid biases introduced by substantially derived (divergent)taxa. We confirm the inclusion of some problematicgenera such as Cedromus or Douglassciurus withinSciuroidea rather than in Aplodontoidea. Ephemeromysand Lophallomys appear as the most basal members of theAplodontoidea, and Epeiromys is the closest outgroup ofthe Sciuroidea-Aplodontoidea clade. The relationshipsamong the ‘‘prosciurines’’ remain unclear, with paraphyleticgenera such as Prosciurus and Haplomys. Theirdiagnoses are reevaluated and a new genus is described.The Aplodontidae, including the clade of the latter, andHaplomys liolophus display a dichotomy betweenAnsomyinae and Aplodontinae, the two crown groups. Thefirst clade formed by the European species argoviensis anddescendens (referred to a new genus) can be proposed as asister group of the species of Ansomys. The second branchof the dichotomy includes the European Plesispermophilusand Sciurodon as basal groups. The species of Parallomysdo not form a clade, and the genus appears paraphyletic.The last dichotomy separates the Allomys clade from the‘meniscomyine’ clade. Comparisons of the selected speciesallow consideration of their patterns of dental evolution(e.g. enlargement of P4, development of a metaloph—protoloph disto-mesial connection, of crescentic shape inmain cusps and ectoloph, of a buccal protruding compressedmesostyle, of a metastylid crest or an anterior spurof the hypoconid, etc.). The split between sciuroids andaplodontoids occurred in North America, and then aplodontoidsdispersed rapidly throughout the whole Holarcticregion. The first aplodontid adaptive radiation took placeeither in North America or in Asia. Periodic exchangesoccurred between Europe, Asia and North America, andthe last radiations (meniscomyines) were restricted inNorth America

Mammal community structure analysis

Peer reviewe

Morphological Variation of the Forelimb and Claw in Neotropical Sigmodontine Rodents (Rodentia: Cricetidae)

The limbs of mammals exhibit a variety of morphologies that reflect the diversity of their habitats and their functional needs, including subtle structural differences in their distal limb integumentary appendages (hooks, claws, adhesive pads). Little is known about structure and function of claws of sigmodontine rodents. Here, we analyze claw shape and forelimb skeleton morphology of 25 species of sigmodontine rodents with different locomotory types (ambulatory, fossorial, natatorial, quadrupedal saltatorial, and scansorial), taking into account their phylogenetic affinities. Qualitative differences in claw shape were examined using digital photographs, and quantitative measurements were made for length, height, and curvature of the claws of all digits, and dimensions of other forelimb skeletal elements. Our results show that both phylogeny and ecological categories explain substantial components of the morphological variation in sigmodontine rodents. Qualitative analysis reveals that non-specialized forms (ambulatory, quadrupedal saltatorial, and scansorial) tend to have high and strongly curved claws, whereas highly specialized forms (fossorial and natatorial) tend to have elongate and smoothly curved claws. However, the quantitative analysis differentiated the fossorial and scansorial by variables related to claw, and natatorial by variables related to bones of the forelimb. No variables that could differentiate ambulatory or quadrupedal saltatorial forms were found, demonstrating that these forms show a generalized morphological pattern. This study indicates that both historical and ecological factors contribute to the evolution of claw length in these groups.Fil: Tulli, María José. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Carrizo, Luz Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina. Universidad Nacional de Misiones; ArgentinaFil: Samuels, J. X.. John Day Fossil Beds National Monument; Estados Unido