Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
172
result(s) for
"GODFREY, STEPHEN J."
Sort by:
A New Genus and Species of Late Miocene Inioid (Cetacea, Odontoceti) from the Meherrin River, North Carolina, U.S.A
A new genus and species of extinct inioid odontocete (Meherrinia isoni) is based on nine partial crania that probably originated from the late Miocene marine Eastover Formation in North Carolina, U.S.A. They were collected from the riverbed of the Meherrin River, a tributary of the Chowan River. Ossification of the mesethmoid and the tight inter-digitation of many sutures indicate that these specimens represent mature individuals. Key characteristics of the new inioid include maxillae that ‘squeeze’ the nasals into a slight hourglass shape and supraoccipital that is deeply wedged between the frontals and maxillae on the vertex. As compared to the extant iniid Inia geoffrensis (Amazon River dolphin) and the extant pontoporiid Pontoporia blainvillei (La Plata dolphin), Meherrinia is more plesiomorphic in having less elevated premaxillary eminences and supraorbital processes. In other respects Meherrinia is intermediate in morphology between the two extant genera of inioids. For example, the essentially symmetrical vertex is intermediate in height between the low and high vertices in Pontoporia blainvillei and Inia geoffrensis, respectively. A cladistic analysis of morphological and molecular data supports a sister-group relationship between Meherrinia and Inia; thus our new taxon is tentatively assigned to the Iniidae. If correct, this is the first iniid represented by diagnostic remains from marine deposits and just the second from North America.
Journal Article
A new cobia (Teleostei, Rachycentridae) species from the Miocene St. Marys Formation along Calvert Cliffs, Maryland, USA
The highly fossiliferous St. Marys Formation is exposed along Calvert Cliffs, Maryland, and comprises one of the best available records of late Miocene life in the northeastern United States. Rachycentron stremphaencus new species, a cobia from the late Miocene (Tortonian) of the St. Marys Formation is described herein on the basis of a single three-dimensional neurocranium. This fossil represents the earliest known occurrence of neurocranial remains of the genus Rachycentron in the record. Rachycentron stremphaencus differs from Rachycentron canadum (Linnaeus, 1766) in many ways. The most obvious include a different ornamentation of the outer surface of the cranial bones; a notably pronounced lateral ridge resulting in a considerable gradient from the dorsal-medial exposure of the frontal to its lateralmost supraorbital margin; the size, shape, and position of the sphenotic that is located in the posterior half of the neurocranium and its lateralmost edge being adjacent to the anteriormost extent of the wedge-shaped trough in the dorsal surface of the skull formed by the lateral and medial ridges; the two contralateral medial ridges forming a proportionately much wider trough on either side of the supraoccipital; the epioccipitals not reaching the rear edge of the neurocranium; and the lack of a conspicuous posterolateral prong of the intercalar.
Journal Article
A new genus and species of late Miocene pontoporiid dolphin (Cetacea: Odontoceti) from the St. Marys Formation in Maryland
Stenasodelphis russellae, a new genus and species of extinct dolphin in the odontocete family Pontoporiidae, is based on a partial cranium of Late Miocene age (Tortonian), circa 9 to 10 Ma, from the Little Cove Point Member of the St. Marys Formation, Maryland, USA. Pontoporiidae are amongst the smallest cetaceans, and this dolphin is one of the smallest reported pontoporiids, being probably less than 1.5 m long. It is also the second oldest named pontoporiid in the world. Stenasodelphis russellae shares with late Middle Miocene Brachydelphis mazeasi (eastern South Pacific) and the latest Miocene and Pliocene species of Parapontoporia (North Pacific) left-skew asymmetry of the cranial vertex. Thus, all of the earliest known Pontoporiidae have cranial asymmetry, in contrast to symmetrical crania in the Pliocene pontoporiids, Pontistes rectifrons and Pliopontos littoralis, and the Recent Franciscana, Pontoporia blainvillei. This suggests that cranial asymmetry may be the primitive character state among stem Pontoporiidae. Autapomorphies of Stenasodelphis russellae include small size, thick cranial bones, wide premaxillary sac fossae, a medial projection of each maxilla onto the lateral side of each nasal, and the highest part of the cranial vertex being formed by the nasals rather than the frontals.
Journal Article
Yaquinacetus meadi, a New Latest Oligocene–Early Miocene Dolphin (Cetacea, Odontoceti, Squaloziphiidae, fam. nov.) from the Nye Mudstone (Oregon, U.S.A.)
Represented by a nearly complete cranium with associated mandible, teeth, and vertebrae, Yaquinacetus meadi is a new genus and species of archaic homodont odontocete from the latest Oligocene–early Miocene (24–19.2 Ma) of Oregon, U.S.A. The new species is characterized by a moderately elongated rostrum bearing approximately 51 alveoli per tooth row and a knob-like, rectangular vertex. Together with Squaloziphius emlongi from the early Miocene of Washington State, Y. meadi constitutes a new odontocete family, Squaloziphiidae, fam. nov., diagnosed by a unique combination of characters, including transversely wide dorsal opening of the mesorostral groove at base of rostrum, followed posteriorly by an abrupt narrowing; thickened lateral margin of the maxilla in the antorbital region making a long and laterally concave crest; and massive, anteroposteriorly and ventrally long postglenoid process of the squamosal. Although sharing with Ziphiidae the presence of transverse premaxillary crests on the vertex, Squaloziphiidae differs in the pterygoid sinus fossa being shorter anteriorly and ventrally; the tubercule of the malleus being less reduced; and lacking a pair of enlarged alveoli for mandibular tusks. Our phylogenetic analysis confirms the sister-group relationship between S. emlongi and Y. meadi, either as late diverging stem odontocetes or as early crown odontocetes, but distant from Ziphiidae. These results confirm the northeastern Pacific as a center of diversification for several groups of archaic homodont odontocetes during the late Oligocene–early Miocene.
Journal Article
A new odontocete (Inioidea, Odontoceti) from the late Neogene of North Carolina, USA
A new monotypic genus of Neogene odontocete (Isoninia borealis) is named on the basis of a partial skull (CMM-V-4061). The holotype was found on the riverbed of the Meherrin River (North Carolina, USA) and probably originated from the Miocene marine Eastover Formation. Deep interdigitation of the cranial sutures indicates that this individual was mature. The new taxon differs from all other delphinidans in the unique combination of the following characters: anteriorly retracted premaxillae and maxillae; premaxillae not contacting nasals; thick nasals with ventrolateral margins deeply imbedded within corresponding troughs in the frontals (this is an apomorphy); nasals with transversely convex dorsal surface; nearly symmetrical vertex; os suturarum (or interparietal or extra folds of the frontals) at the vertex; large dorsal infraorbital foramen level with the posterior margin of the external bony nares; and a postorbital recess on the ventrolateral face of the frontal below and behind the postorbital process of the frontal. This odontocete exhibits two small but pronounced concavities on the cerebral face of the frontal/presphenoid that are presumed to have held vestigial olfactory bulbs in life. Inioidea is only diagnosed by a single unequivocal synapomorphy: width across nasals and nares subequal. Isoninia shares this feature with other inioids and forms the basis for the placement of Isoninia within this clade. A relatively high vertex coupled with a supraoccipital that is deeply wedged between the frontals suggests placement of this new inioid species within the family Iniidae. This is the second inioid described from the Eastover Formation (the other beingMeherrinia isoni). This new species adds new cranial morphology and a new combination of cranial characters to this taxonomically small but growing group of mostly marine and mostly Western Hemisphere odontocetes (urn:lsid:zoobank.org:pub:E8B817CA-B250-42B3-9365-36EFBFE351C9).
Journal Article
Tilefish (Teleostei, Malacanthidae) Remains from the Miocene Calvert Formation, Maryland and Virginia: Taxonomical and Paleoecological Remarks
The spectacularly fossiliferous Calvert Formation is largely exposed in Maryland and Virginia and comprises the best available record of middle Miocene life in the northeastern United States. Lopholatilus ereborensis, sp. nov., a new tilefish from the middle Miocene (Langhian) of the Calvert Formation, is described herein based on 15 well-preserved three-dimensional partially complete articulated skeletons. These fossils consist primarily of cranial remains and represent the earliest known occurrence of the genus Lopholatilus in the record. Lopholatilus ereborensis is characterized by moderately deep head and short snout, occipital region of the neurocranium obliquely sloping, epioccipital spine extending posteriorly beyond the supraoccipital crest, remarkably shortened ascending process of the premaxilla, villiform teeth on dentary restricted to the symphyseal region, horizontal arm of the preopercle short, and angle formed by vertical and horizontal arms of the preopercle measuring about 120°. Taphonomic and paleoecological considerations suggest that Lopholatilus ereborensis inhabited long funnel-shaped vertical burrows self-excavated within the stable and cohesive bottoms of the outer continental shelf of the Salisbury Embayment, and possibly of other parts of the western North Atlantic outer shelf and upper slope that were characterized by relatively warm oxygenated waters. In that context, the three-dimensional preservation of the articulated skeletons of Lopholatilus ereborensis might represent the product of an abrupt burial resulting from the collapse of the upper part of the burrows. Cylindrical-shaped trace fossils (domichnia) penetrating the fine-grained sands of the middle part of the Calvert Formation are proposed to have been produced by Lopholatilus ereborensis.
Journal Article
A new specimen of Agorophius pygmaeus (Agorophiidae, Odontoceti, Cetacea) from the early Oligocene Ashley Formation of South Carolina, USA
The holotype partial skull of Agorophius pygmaeus (the monotypic form for both the genus Agorophius and the Family Agorophiidae) has been missing for approximately 140 years. Since the discovery of Agorophius pygmaeus, many additional taxa and specimens have been placed in the Family Agorophiidae, only to be reclassified and removed later. This has created confusion as to what is and what is not an agorophiid and a lack of clarity as to what characteristics delimit the Agorophiidae. A newly discovered skull of an agorophiid recently collected from an underwater cliff face of the Ashley River, South Carolina, USA, is assigned to Agorophius pygmaeus. It derives from the base of the Ashley Formation (early Oligocene). The new specimen consists of most of the skull and periotics, which are well preserved and described for the first time in an agorophiid. The new specimen provides an opportunity to diagnose the Agorophiidae and place the genus and species within the phylogenetic context of the early odontocete radiation in the Oligocene, along with other taxa such as the Ashleycetidae, Mirocetidae, Patriocetidae, Simocetidae, Waipatiidae, and Xenorophidae. Based on this new understanding, Agorophiidae are known with certainty only from the early Oligocene of South Carolina, with other undescribed, potential agorophiid specimens from the Oligocene of the North Pacific region (Japan, Mexico, and Washington State).
Journal Article
Variation in Composition and Abundance of Miocene Shark Teeth from Calvert Cliffs, Maryland
Shark teeth are the most common vertebrate fossils found along the western shore of Chesapeake Bay at Calvert Cliffs in Maryland. The stratigraphic distribution of teeth within the cliffs has not yet been documented. We utilized museum collections of in situ teeth to access their distribution within stratigraphic beds and a large selection of float teeth retrieved from Calvert County beaches as a proxy for the distribution of teeth within stratigraphic beds and across underlying beaches. Museum collections provide 1,866 teeth recorded in situ; float collections yield a total of 24,409 teeth. These data sets offer different, but complementary, results. Miocene sediments along Calvert Cliffs comprise the Calvert, Choptank, and St. Marys formations. Over 96% of all teeth in the in situ data set derive from the Calvert Formation, likely due to favorable paleoenvironmental conditions for sharks. The non-uniform stratigraphic distribution of teeth is further supported by an uneven distribution of teeth collected on beaches below the cliffs. Samples from northern localities contained more float specimens; cliffs in this area are composed almost entirely of the Calvert Formation. Fifteen genera are represented in the in situ and float collections. The main constituents are Carcharhinus spp., Hemipristis serra, Galeocerdo spp., Isurus spp., and Carcharias spp. Most of these genera exhibit significant unidirectional trends in the proportional abundance of teeth across Calvert Cliffs beaches. Factors influencing these variations remain unclear, but the overall dominance of carcharhiniforms over lamniform and other sharks observed for the Miocene persists in modern nearshore environments.
Journal Article
Stargazer (Teleostei, Uranoscopidae) Cranial Remains from the Miocene Calvert Cliffs, Maryland, U.S.A. (St. Marys Formation, Chesapeake Group)
Fishes of the genus Astroscopus are anatomically distinctive within the family Uranoscopidae, mostly because they are characterized by internal nares and are the only marine teleosts known to possess electric organs derived from extraocular muscles. The new world genus Astroscopus contains three extant species from tropical to temperate coastal waters of both sides of the American continent, plus fragmented isolated bones and otoliths of an indeterminate fossil species from the Pliocene and Pleistocene of the Coastal Plain of the eastern United States. Astroscopus countermani, sp. nov., a new stargazer from the Miocene (Tortonian) of Calvert Cliffs (Maryland), is described herein based on well-preserved three-dimensional cranial remains. These cranial remains represent the earliest known skeletal record for the family Uranoscopidae, as well as the earliest occurrence of the genus Astroscopus in the fossil record. Astroscopus countermani is typified by a unique neurocranial appearence, an obliterated orbital foramen, and a prominent ornamented tuberosity arising from the dorsolateral surface of the hyomandibula. Among the anatomical distinctive features of Astroscopus countermani is the relative enlargement of the interorbital portion of the neurocranium (with respect to its extant congeners), which appears to be related to a reduced development of the electrogenic organs. Paleoecological considerations suggest that Astroscopus countermani was a predatory fish that inhabited the subtropical and warm temperate Atlantic marine and paralic waters of North America during the Miocene.
Journal Article