Papers by Patrick OConnor
Acta Palaeontologica Polonica, 2016
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ABSTRACT ABSTRACT-Living mammals are distinguished from other extant tetrapods by adaptations for... more ABSTRACT ABSTRACT-Living mammals are distinguished from other extant tetrapods by adaptations for improved senses of hearing, touch, and smell. These adaptations, and concomitant reductions in visual anatomy, evolved during the Mesozoic in the mammalian and therian stem lineages. Here, we present a comparative study of the sensory anatomy of the Late Cretaceous gondwanatherian mammaliaform Vintana sertichi in order to draw inferences regarding its sensory abilities and sensory ecology. Our analyses demonstrate that Vintana has relatively large orbits that may have accommodated large eyes. Vintana also possessed cochlear primary and secondary osseous laminae and a cochlear canal that was relatively longer than in non-mammaliaform cynodonts but shorter than in extant therians. These features suggest that Vintana had some capacity for high-frequency hearing (i.e., >20kHz), but that its cochlea may have encoded a more limited range of frequencies than the cochleas of most extant therians. The semicircular canals of Vintana have large radii of curvature and are nearly orthogonal, suggesting high sensitivity to angular head accelerations. These vestibular features may have evolved in order to stabilize large eyes during rapid and/or agile locomotion. Combined with evidence for large olfactory bulbs and a large trigeminal endocast, these data reveal that Vintana possessed a unique suite of sensory adaptations that distinguish it from other Mesozoic mammaliaforms. If these inferences are correct, then Vintana was probably a large-eyed and agile species, with a keen sense of smell and better high-frequency hearing than most other Mesozoic mammaliaforms. SUPPLEMENTAL DATA-Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
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ABSTRACT The Gondwanatheria are an enigmatic clade of Cretaceous and Paleogene mammals known from... more ABSTRACT The Gondwanatheria are an enigmatic clade of Cretaceous and Paleogene mammals known from South America, Africa, Madagascar, India, and the Antarctic Peninsula. The eight valid species-each belonging to a monotypic genus and the first of which was described only 30years ago-are represented almost exclusively by isolated teeth, in addition to fragmentary dentaries attributed to Sudamerica, Gondwanatherium, Ferugliotherium, and an unnamed taxon from Tanzania. No cranial (skull exclusive of lower jaw) or postcranial material has heretofore been assigned to the Gondwanatheria, a severe limitation that has precluded a comprehensive assessment of phylogenetic affinities. Here we describe, in detail, the first cranial specimen of a gondwanatherian mammal. This material consists of a complete and well-preserved cranium of the sudamericid Vintana sertichi, recovered from the Upper Cretaceous (Maastrichtian) Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. Salient features of the cranium include elongate, scimitar-like jugal flanges, huge orbits, strong klinorhynchy, and a vaulted nuchal region. Micro-computed tomography greatly facilitated the delineation of sutures and the description of internal morphology. The cranial features of Vintana are compared with those of a broad range of synapsids, with particular concentration on other Mesozoic mammaliaforms. The cranium of Vintana exhibits a mosaic of extremely primitive and extremely derived features. It is the second largest known for a Mesozoic mammaliaform, superseded only by that of the eutriconodontan Repenomamus giganticus from the Early Cretaceous of China. Vintana is the largest known Late Cretaceous mammaliaform; it is also the largest known Mesozoic mammaliaform from Gondwana. SUPPLEMENTAL DATA-Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
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Nature, 2005
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Journal of African Earth Sciences, 2006
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Journal of African Earth Sciences, 1998
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Annals of the Missouri Botanical Garden, 2006
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Annals of the Missouri …, 2006
The Mahajanga Basin Project, initiated in 1993 and centered in Upper Cretaceous strata of northwe... more The Mahajanga Basin Project, initiated in 1993 and centered in Upper Cretaceous strata of northwestern Madagascar, has resulted in the discovery of some of the most complete, well-preserved, and significant specimens of Late Cretaceous vertebrate ...
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Cretaceous Research, Oct 31, 2004
The Red Sandstone Group comprises a succession of red sandstones and mudstones exposed in the Ruk... more The Red Sandstone Group comprises a succession of red sandstones and mudstones exposed in the Rukwa and Malawi rift basins of southwestern Tanzania and northern Malawi. Stratigraphic, sedimentologic, and paleontologic investigations of the Red Sandstone Group in the Songwe Basin (a sub-basin of the Rukwa Rift Basin) help clarify the age and depositional history of these strata, which have previously been assigned ages ranging from Middle Jurassic to late Miocene. These seemingly incompatible Mesozoic ...
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Journal of African Earth …, 2006
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Papers by Patrick OConnor