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Well-preserved Early Silurian radiolarians were recovered from siliceous rock fragments contained in a limestone boulder from the Road River Formation, Yukon River area, east-central Alaska. The radiolarians represent five genera, one of which, Parasecuicollacta, is new, and 17 species, nine of which are new: Secuicollacta magnitesta, S. tatondukensis, S. parvitesta, S. alaskensis, Parasecuicollacta bipola, P. hexactina, P. multispinosa, P. nannoglobosa, and Diparvapila pygmaea. Among the 17 species, 11 belong to the family Rotasphaeridae. The ectopically placed spicule, which is the diagnostic characteristic of the subfamily Secuicollactiniinae within the family Haplentactiniidae, is shown to be one of the primary units, a diagnostic feature of the family Rotasphaeridae. Three species are assigned to the family Haplotaeniatumidae, which is newly established in this paper. The family is characterized by the concentric and spiral arrangement of shell with a proloculus and commonly the presence of a pylome, and by the absence of an internal spicule. Several other taxa are extremely rare and are of uncertain taxonomic position. This fauna is characterized by very plentiful rotasphaerids, whereas all the other radiolarian taxa are very rare.
The Road River fauna is similar to that from the Cherry Spring Chert of Nevada, thought to be late Rhuddanian based on a sparse graptolite fauna, and is very similar to an unreported Early Silurian Canadian Arctic fauna, whose stratigraphic range based on the graptolite fauna is within the early Telychian. Conodonts, chitinozoans, scolecodonts, and graptolites were also recovered from the siliceous rock fragments. Five genera and seven species of chitinozoans, four genera and five species of conodonts, and two uncertain taxa of graptolites were identified. Their biostratigraphy indicates that the Alaskan radiolarian fauna belongs to the upper Aeronian to lower Telychian of the Llandoverian.
Seven new monoplacophoran genera and species are described and figured from Cambrian and Lower Ordovician strata of the Ozark Uplift of Missouri; Biloboconus frizelli, Ulrichoconus bonneterrense, Potosiplina delorensis, Gayneoconus echolsi, Irondalia irondalensis, Titanoplina meramecensis, and Wildernessia inexpectans. A new species of Kirengella, K. oregonensis, is described, and Hypseloconus compressus (Ulrich and Bridge, 1930, and H. expansusStinchcomb, 1986, are assigned to the genus Kirengella. The morphology of Kirengella is compared to highly arched forms of the plated mollusk genus Preacanthochiton and is found to converge with them. Association with stromatolite reefs of both Kirengella and plated mollusks is noted.
Seven crinoid species and one very unusual column are recognized from the Ordovician, Dobrotivian (Llandeillian Stage) to Ashgill of Spain. Three previously described species, Heviacrinus melendeziGil Cid, Domínguez, and Silván, 1996; Coralcrinus sarachagorumGil Cid, Domínguez, and Silván, 1998; and Ortsaecrinus cocaeGil Cid, Domínguez, Torres, and Jiménez, 1999, are considered, and four new species assigned to three new genera are described herein, including Visocrinus castelli, Fresnedacrinus ibericus, Morenacrinus silvani, and Merocrinus millanae. Previous reports of Ramseyocrinus from Spain have been revised, and we agree that this disparid is not presently known from Spain. These crinoids represent the largest Ordovician crinoid fauna from Gondwana, including these localities and those from the Montagne Noire along peri-Gondwana during the Ordovician. The crinoids reported here, from the Montes de Toledo and Sierra Morena, and the Ordovician crinoids from Montagne Noire have very little in common with Ordovician crinoids from the Prague Basin. Thus, these new data support paleogeographic plate positioning that allows for either paleoclimatic, paleoenvironmental, or paleogeographic isolation between the Prague Basin and peri-Gondwana.
Quintuplexacrinus new genus with Dendrocrinus oswegoensisMeek and Worthen (1868) as the type and only known species is described and assigned to the Merocrinidae. The new genus is characterized by a unique stem with a highly pentalobate axial canal; the distal column is highly differentiated with large and very high nodals and thin internodals. A cladistic analysis indicates that Quintuplexacrinus n. gen. is closely related to Praecupulocrinus. The numbers of the various orders of brachs are independent of the size and age of the animals. Within the arms only the numbers of primibrachs and secundibrachs are positively correlated. Some variation is related to position of the rays. The C ray bears the smallest number of primibrachs. The outer half-rays possess more numerous tertibrachs than the inner ones. Aboral cup growth produces a wide-based and distally expanding outline at all sizes. In general, the widths of the cup and the cup's component plates are positively allometric relative to their heights. Likewise, the width:height ratios of the proximal brachs, primibrachs through tertibrachs, increase in older and larger individuals because the widths grow faster than the heights. The number of columnals in both the proximal and distal stem regions is typically stabilized throughout ontogeny. However, the entire stem becomes longer and wider in larger specimens due to calcite deposition on the columnals. Development of the columnals is isometric so their shapes do not change with size and age.
Codellaster keepersae new genus and species, from the Upper Cretaceous Codell Sandstone Member of the Carlile Shale of Colorado (U.S.A.), is assigned to the asteroid (Echinodermata) family Goniasteridae. Although clearly a goniasterid, the flattened body form and details of morphology of C. keepersae are remarkably similar to corresponding features of the modern astropectinid Astropecten regalis and also of the luidiid Luidia (Platasterias) latiradiata. The discovery facies of C. keepersae includes low-angle crossbeds and asymmetrical ripple marks that are suggestive of a very shallow marine environment. Both the modern species occur in shallow, turbulent settings, and homeomorphy beween ancient and modern asteroids suggests similar selective pressures and evolutionary responses. Limited evidence suggests goniasterids might have been more common in shallower waters during the Cretaceous than they are today, and absence of modern Codellaster-like goniasterids indicates that the family abandoned these habitats, although the fundamental morphological response to such settings remained viable for asteroid organization.
One new genus, Kalops, and two new species, K. monophrys and K. diophrys, are described from the Carboniferous (Namurian) marine Bear Gulch limestone of Montana (USA). The most conspicuous features of these elongate fusiform actinopterygians consist of one or two rows of anamestic supraorbital bones, a mosaic of suborbitals, and the presence of two rows of extrascapulars in one species. Discussions of their anatomical, morphometrical, and growth characters result in their placement in the same genus. Comparisons with other Palaeozoic actinopterygians show that Kalops is a Palaeoniscimorpha (=basal Actinopteri sensu Patterson).
The aïstopod family Phlegethontiidae is restudied based on new specimens from Pit 11 of Mazon Creek, Illinois, and the coal shales of Nýřany, Czech Republic, as well as most available specimens from North America. Phlegethontiids have highly fenestrate skulls, with orbits placed just anterior their skull's mid point. Dermal skull bones are greatly reduced in number and limited in extent, whereas the endochondral braincase is hyperossified. The frontals are fused medially and enclose the parietal foramen and anterior sagittal crest. As in most other aïstopods, the quadrate, pterygoid, and epipterygoid are fused into a composite bone, the palatoquadrate complex. Details of cranial anatomy contradict a previous model of cranial kinesis by severely limiting the skull's potential mobility. Remnants of the pectoral girdle are present, perhaps due to the presence of an operculum–opercularis-like connection to the stapes. No remnants of the pelvis are present.
Three species are recognised within the family. Phlegethontia linearis has short anterior vertebrae, high neural spines on at least the anterior four vertebrae, and vertebrae number between 230–250 in total. Phlegethontia longissima has low neural spines throughout the column, anterior vertebrae that are twice as long as P. linearis, and only 200–210 total vertebrae. Sillerpeton permianum, known from a single braincase and an unassociated string of vertebrae, is distinguished from Phlegethontia by the retention of a separate foramen for the passage of the occulomotor nerve. Phlegethontia “phanerhalpa” is a tiny braincase fragment that differs from the other species of Phlegethontia only in the placement of the jugular foramen relative to the centre of the foramen magnum. This is probably a size-related feature, and P. “phanerhalpa” is considered a nomen dubium.
The dicynodont anomodont Odontocyclops whaitsi, from the Late Permian Madumabisa Mudstone of Zambia, is redescribed and its phylogenetic relationships are considered. The genus is characterized by a two autapomorphies, elongate nasal bosses and a concave dorsal surface of the snout; it also possesses wide exposure of the parietals on the intertemporal skull roof, the presence of a postcaniniform crest, the absence of a labial fossa, and the presence of a dorsal process on the anterior ramus of the epipterygoid footplate. In addition, newly recognized specimens collected in South Africa extend the known geographic range of the genus and allow description of the humerus and scapula for the first time. Cladistic analysis of a data set including Odontocyclops and 18 other well-known South African dicynodont genera does not support the hypothesis that Odontocyclops is a close relative of Dicynodon or of Triassic dicynodonts such as Kannemeyeria. Instead, a close relationship with Oudenodon and Rhachiocephalus is proposed. The presence of Odontocyclops in South Africa and Zambia makes it potentially valuable for more precise biostratigraphic correlation between the sediments of the Karoo Basin and the Luangwa Valley.
A well-preserved crocodyliform specimen from the Maastrichtian or Paleocene of Mali preserves the braincase and posterior dermatocranium. It is referred to Dyrosauridae on the basis of several derived features (a prominent anterior process of the postorbital, discrete occipital processes on the exoccipitals, significant quadratojugal contribution to jaw joint) and tentatively referred to Rhabdognathus on the basis of supratemporal fenestra shape. The lacrymal and prefrontal are relatively short compared with those published for other dyrosaurids. The palatines border the internal choanae anteriorly, and the choanae are divided by a midline septum derived from the pterygoids. The prefrontal pillars are mediolaterally broad and contact the palate ventrally. One stapes is preserved in place. The basicranial pneumatic system is very unusual, in that the anterior and posterior branches of the median eustachian canal are both separate at the palatal surface, and the pterygoids form part of the border for the anterior branch. The lateral eustachian openings lie within fossae on the lateral surface of the braincase and face laterally, with a descending process of the exoccipital nearly intersecting the opening. The braincase and surrounding dermal bones are elongate anteroposteriorly, and the postorbital's posterior ramus extends along the posterodorsal margin of the infratemporal fenestra. The quadrate ramus projects ventrally. These observations clarify character optimizations in previous phylogenetic analyses of Crocodyliformes.
A new collection of lagomorphs and rodents from the Deer Park B local fauna (l.f.) of Meade County, Kansas is described and compared with other small mammal assemblages of the Meade Basin, including the underlying Deer Park A l.f. Deer Park A was correctly assigned by Hibbard to the Blancan, bridging the gap between earlier Blancan faunas such as Fox Canyon and the late Blancan Sanders l.f. Recent fieldwork indicates that the Deer Park quarries may lie in the Rexroad Formation, rather than in the Ballard Formation as previously assumed. The geology and extinct mammalian contingent at Deer Park suggest that the lower horizon of Deer Park A was an active spring that gradually turned into a marshy environment during Deer Park B time. The rodents of Deer Park B are indicative of an open prairie ecosystem that might have been somewhat more arid than that of southwestern Kansas today.
Three new species of Viverravidae (Carnivora: Miacoidea) are described: Protictis simpsoni, P. minor, and Bryanictis paulus. Holotypes and referred specimens are from the Angel Peak area, Kutz Canyon, San Juan Basin, New Mexico and are of middle Torrejonian age (middle Paleocene). The holotype of Protictis simpsoni includes a skull—the oldest known skull of the Order Carnivora. The locality is narrowly restricted stratigraphically and geographically, and specimens are better preserved than most other viverravid specimens of San Juan Basin strata.