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An Early Ordovician (Floian) asterozoan (Echinodermata) of problematic class-level affinities

  • Daniel B. Blake (a1), Forest J. Gahn (a2) and Thomas E. Guensburg (a3)

Abstract

Falloaster anquiroisitus new genus new species (Asterozoa, Echinodermata) is described from the Floian (Early Ordovician) Garden City Formation of Idaho. The new taxon is known from a single small specimen. Because of weathering, remaining disk elements are incomplete. Dorsal surfaces of the ambulacral ossicles of two arms are available, one well preserved, whereas those of a third arm expose the ambulacrals essentially as they would appear in ventral view. Ambulacral ossicles were all but entirely lost on the remaining two arms.

Albeit asterozoan, F. anquiroisitus is not assignable at the class level. It is suggestive of the Asteroidea in presence of a domal disk, five abruptly tapering triangular, arched arms, and ambulacral ossicles vaulted to form a furrow. Ambulacral morphology, including the presence of very large podial pores, is unlike that of early asteroids. In addition, no adambulacral or other virgal-series derivatives are present; ambital framework ossicles are absent; a single series of enlarged, plate-like arm ossicles, one series on each side of the arm, come together at the arm midline; and the plate-like series were supported laterally by recurved ambulacral margins. Only remnants of the disk near the periphery survive, these of overall expression unlike any other echinoderm, including asterozoans. The mouth frame is unknown. Falloaster anquiroisitus is argued to represent an extinct lineage apart from the four recognized asterozoan classes, thereby joining a limited number of other problematic early Asterozoa.

UUID: http://zoobank.org/a13a5417-44b6-4ac3-90cf-9dc8fb5902bd

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Adrain, J.M., McAdams, N.E.B., and Westrop, S.R., 2009, Trilobite biostratigraphy and revised bases of the Tulean and Blackhillsian Stages of the Ibexian Series, Lower Ordovician, western United States: Memoirs of the Association of Australian Palaeontologists, v. 37, p. 541610.
Blake, D.B., 1995, A new asteroid genus from the Carboniferous of Ireland and its phylogenetic position and paleoecology: Irish Journal of Earth Sciences, v. 14, p. 6580.
Blake, D.B., 2000, An Archegonaster-like somasteroid (Echinodermata) from Pomeroy, Co. Tyrone, Northern Ireland: Irish Journal of Earth Sciences, v. 18, p. 8999.
Blake, D.B., 2013, Early asterozoan (Echinodermata) diversification: A paleontologic quandary: Journal of Paleontology, v. 87, p. 353372.
Blake, D.B., 2014, Two Ordovician asterozoans (Echinodermata) of problematic affinities: Journal of Paleontology, v. 88, p. 11631173.
Blake, D.B., 2018, Toward a History of the Paleozoic Asteroidea (Echinodermata): Bulletins of American Paleontology 394, 96 p.
Blake, D.B., and Guensburg, T.E., 1989, Illusioluidia teneryi n. gen. and sp. (Asteroidea: Echinodermata) from the Pennsylvanian of Texas, and its homeomorphy with the extant genus Luidia Forbes: Journal of Paleontology, v. 63, p. 331340.
Blake, D.B., and Guensburg, T.E., 2015, The class Somasteroidea (Echinodermata, Asterozoa): Morphology and occurrence: Journal of Paleontology, v. 89, p. 465486.
Blake, D.B., Zamora, S., and García-Alcalde, J.L., 2015, A new Devonian asteroid-like ophiuroid from Spain: Geologica Acta, v. 13, p. 335343.
Jaekel, O., 1923, Zur Morphogenie der Asterozoa: Palaeontologischen Zeitschrift, v. 5, p. 344350.
Mikulás, R., 1992, The ichnogenus Asteriacites: palenvironmental trends: Vestnik Ceského Geologického Ústavu, v. 67, p. 423433.
Mooi, R., and David, B., 1998, Evolution within a bizarre phylum: Homologies of first echinoderms: American Zoologist, v. 38, p. 965974.
Mooi, R., and David, B., 2000, What a new model of skeletal homologies tells us about asteroid evolution: American Zoologist, v. 40, p. 326339.
Mooi, R., and David, B., 2008, Radial symmetry, the anterior/posterior axis, and echinoderm Hox genes: Annual Review of Ecology, Evolution, and Systematics, v. 39, p. 4362.
Schöndorf, F., 1910, Über einige “Ophiuriden und Asteriden” des englischen Silur und ihre Bedeutung für die Systematik paläozoischer Seesterne: Jahrbüchern des Nassauischen Vereins für Naturkunde in Wiesbaden, v. 63, p. 206256.
Schuchert, C., 1915, Revision of Paleozoic Stelleroidea with special reference to North American Asteroidea: Bulletin of the U.S. National Museum 88, 311 p.
Shackleton, J.D., 2005, Skeletal homologies, phylogeny and classification of the earliest asterozoan echinoderms: Journal of Systematic Palaeontology, v. 3, p. 29114.
Smith, A.B., and Jell, P.A., 1990, Cambrian edrioasteroids from Australia and the origin of starfishes: Memoirs of the Queensland Museum, v. 28, p. 715778.
Spencer, W.K., 1914–1940, The British Palaeozoic Asterozoa: Palaeontographical Society of London Monograph, pts. 1–10 (for 1913–1940), 540 p.
Spencer, W.K., 1951, Early Palaeozoic starfish: Philosophical Transactions of the Royal Society, London B, v. 235, p. 87129.
Spencer, W.K., and Wright, C.W., 1966, Asterozoans, in Moore, R.C., ed., Treatise on Invertebrate Paleontology, part U, Echinodermata 3, Volume 1: Boulder, Colorado, and Lawrence, Kansas, The Geological Society of America and University of Kansas Press, p. U4U107.
Thoral, M., 1935, Contribution à l’étude paléontologique de l'Ordovicien inférieur de la Montagne Noire et révision sommaire de la faune cambrienne de la Montagne Noire [Ph.D. thesis]: Paris, l'Université de Paris, 363 p.
Ubaghs, G., 1967, General characters of Echinodermata, in Moore, R.C., ed., Treatise on Invertebrate Paleontology, part S, Echinodermata 1, Volume 1: Boulder, Colorado, and Lawrence, Kansas, The Geological Society of America and University of Kansas Press, p. S3S60.
Villier, L., Brayard, A., Bylund, K.G., Jenks, J.F., Escarguel, G., Loivier, N., Stephen, D.A., Vennin, E., and Fara, E., 2017, Superstesaster promissor gen. et sp. nov., a new starfish (Echinodermata, Asteroidea) from the Early Triassic of Utah, USA, filling a major gap in the phylogeny of asteroids: Journal of Systematic Palaeontology, v. 16, p. 395415, https://doi.org/10.1080/14772019.2017.1308972.
Zittel, K.A., 1895, Grundzüge der Palaeontologie (Palaeozoologie): Munich, R. Oldenbourg, 971 p.

An Early Ordovician (Floian) asterozoan (Echinodermata) of problematic class-level affinities

  • Daniel B. Blake (a1), Forest J. Gahn (a2) and Thomas E. Guensburg (a3)

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