Some Albian (Cretaceous) asteroids (Echinodermata) from Texas and their paleobiological implications

Abstract

An asteroid fauna is described from the Albian (Cretaceous) interval of the Washita Group of central Texas. New genera and species are Alkaidia sumralli, (Benthopectinidae), Capellia mauricei (Goniasteridae), and Betelgeusia reidi (Radiasteridae). Additional new genera are Fomalhautia (Goniasteridae), and Denebia and Altairia (Ophidiasteridae). Crateraster texensis (Goniasteridae), new combination, is similar to the European type species, C. quinqueloba. An unnamed species of Crateraster and an unassigned goniasterid are also present. All Washita genera are extinct, but all belong to extant families. The fauna is largely distinct from that of the somewhat younger European Cretaceous chalk.The Radiasteridae (e.g., Betelgeusia) is inferred to hold a basal position in the Paxillosida; Betelgeusia extends the range of the family back to the Cretaceous, closer to the diversification of the living asteroid orders. Asteroids capable of burying themselves in sediment (and only self-buriers) share some form of channelization for the passage of water currents between the primary ossicles of the body surface. Channels in Betelgeusia indicate semi-infaunal habits similar to those of living Astropecten and Luidia. Betelgeusia represents the third semi-infaunal paxillosidan family now known from the Cretaceous, although none are known from older rocks, suggesting a broadening of the asteroid adaptive zone during the Cretaceous. The Goniasteridae, Radiasteridae, and Benthopectinidae are less important in shelf settings today than they appear to have been during Washita deposition, whereas the Astropectinidae, Luidiidae, and the Echinasteridae are absent from the Washita although they are common today in similar settings.

A new asteroid (Echinodermata) faunule from the Early Cretaceous (Barremian) of Morocco

“…Schulz and Weitschat (1971 treated Cretaceous asteroids of Germany, and Brü nnich Nielsen (1943), Rasmussen (1950), and Jagt (2000) studied Cretaceous and Cretaceous-Paleogene asterozoans from Denmark, the Netherlands, and Belgium. Beyond Europe, Blake and Reid (1998) treated middle Cretaceous asteroids from Texas, and Hess and Blake (1995), Villier et al (2007), and the present study treat Cretaceous occurrences from north Africa.…”

“…Expression of the actinal ossicles and the actinal interbrachia provide a character complex of apomorphies supporting a monophyletic Radiasteridae sensu Blake and Reid (1998). In brief, actinals are uniform, strongly overlapping, spinose, and closely aligned in narrow, regular rows (Blake, 1987, p. 506, character 1;Blake and Reid, 1998, fig.…”

“…Comparisons across time, a concern of Hennig (1966), can miss gradational change. For example, perhaps a now-smaller taxon suffered significant extinctions while a larger diversified; the hypothesis on evolutionary ecology of Blake and Reid (1998) and below suggests disappearance of the Radiasteridae from shallow water.…”

Un astropectínido (Echinodermata, Asteroidea) cretácico temprano de Patagonia (Argentina): Una nueva especie y el registro más antiguo de la familia para el Hemisferio Sur.

“…They are capable of self-burial due to the presence of deep fascioles, which are deep in Tethyaster. Astropecten and Luidia Forbes, 1839, two common extant paxillosidan genera, are capable of self-burial, pushing sediment laterally from beneath their bodies and gradually sinking beneath the surface (Heddle, 1967); in both these genera, the presence of fascioles allows unobstructed water 218 An EArly CrEtACEous AstropECtinid (EChinodErmAtA, AstEroidEA) from pAtAgoniA (ArgEntinA)... flow over the animal's body surface, thereby aiding in self-burial (Blake and Aronson, 1998;Blake and Reid, 1998). Blake and Aronson (1998) point out that asteroid self-burial evolved in the Cretaceous, and that 'the oldest clearly identified fasciole-bearing taxon is from the Early Cretaceous' (Hauterivian and Barremian; Hess and Blake 1995).…”

On some Panamerican Cretaceous crabs (Decapoda: Raninoida)

“…Within Tarrant County, Texas, the Paw Paw Formation consists of approximately 8 m of brown arenaceous clay with cross-bedded sandstone and ironstone concretions that crop out along a narrow northsouth band across the county (Root, 1975;Kennedy, 2004). The Paw Paw Formation is highly fossiliferous in marine invertebrates (Adkins, 1918;Hendricks, 1967;Blake and Reid, 1998) and vertebrates (Lee, 1994(Lee, , 1996Siverson et al, 2007). Fossil decapod crustaceans have been previously reported by Rathbun (1935), Hendricks (1967), Schweitzer Hopkins et al (1999, and Haj and Feldmann (2002).…”