Chariocrinus(Crinoidea: Articulata) from the Latady Formation, Behrendt and Hauberg Mountains, Ellsworth Land, Antarctica

Abstract

Specimens of a late Bajocian to early Callovian isocrinid assigned to Pentacrinites cf. P. californicus (Clark), and specimens collected by Hikuroa in 1999-2000, are described as a new species of Chariocrinus. All specimens were collected from rock exposures of the Latady Formation at eight localities in the Behrendt and Hauberg Mountains, Ellsworth Land, Antarctica.The fauna, preserved in situ at all localities, is essentially complete, but due to tectonism, localities may have been moved many kilometres from their original position. Chariocrinus latadiensis n. sp. is compared with congeneric species and those of Hispidocrinus. It is the first record of the genus in the Southern Hemisphere, which has European Tethyan affinities. Columnals are pentastellate to pentalobate, and the symplectial articula appear diagnostic of Hispidocrinus but are included in Chariocrinus on the basis of spineless axillaries and fused adjacent crenulae; those of Hispidocrinus are spined and separated by a furrow or smooth band, respectively.A single pluricolumnal (?Apiocrinus) is the only associated crinoid found at any of the localities. Chariocrinus latadiensis lived a semi-sessile existence on a volcarenite substrate in association with vagrant ammonites, epifaunal and infaunal bivalves, and epifaunal brachiopods. The benthic taxa lived in shallow, low energy marine environments in the Middle Jurassic, part of a submarine back-arc basin near the shore off southeastern Gondwana.

A new stratigraphy for the Latady Basin, Antarctic Peninsula: Part 2, Latady Group and basin evolution

“…The community is dominated by epifaunal, medium-sized, mainly coarsely ribbed Retroceramus and Inoceramus bivavles. Eagle & Hikuroa (2003) described similar crinoids from the site at Mount Hirman. described some poorly preserved ammonites from Witte Nunataks that he provisionally assigned to Torquasphintes and the specimens collected here have the same characteristics.…”

“…Late Middle Jurassic faunas have been described from the Behrendt Mountains (Quilty, 1970(Quilty, , 1972(Quilty, , 1983Eagle & Hikuroa, 2003). The type section in the Latady Mountains represents only a fraction of the range of lithologies seen in the whole basin and much of the sedimentary detail has been masked by subsequent metamorphism.…”

The palaeoecology of two Scottish encrinites: Jurassic crinoid assemblages from the Trotternish Peninsula, Isle of Skye, Scotland

“…The columnal height is low relative to diameter compared to other members of the family cirral scars are also significantly smaller. Some species of Chariocrinus have pentastellate to pentalobate columnals with symplectial articula that appear diagnostic of Hispidocrinus (Eagle & Hikuroa 2003). However, Eagle & Hikuroa (2003) assigned these specimens to the Chariocrinus latadiensis (Middle Jurassic of Antarctica) based on their spineless axillaries and fused adjacent crenulae.…”

“…Some species of Chariocrinus have pentastellate to pentalobate columnals with symplectial articula that appear diagnostic of Hispidocrinus (Eagle & Hikuroa 2003). However, Eagle & Hikuroa (2003) assigned these specimens to the Chariocrinus latadiensis (Middle Jurassic of Antarctica) based on their spineless axillaries and fused adjacent crenulae. In-fact Simms (1989) assigned Chariocrinus leuthardti to Hispidocrinus solely on the presence of large conical spines (Salamon & Zato 2007).…”

A diverse crinoid fauna from the Middle Jurassic (Upper Bajocian–Callovian) of the Polish Jura Chain and Holy Cross Mountains (south-central Poland)

“…-Hess (1972) Hess (1972), were shown many times (e.g. Hess 1972Hess , 1999Klikushin 1979Klikushin , 1992G∏uchowski 1987;Eagle & Hikuroa 2003). Simms (1989), on the other hand, claimed that such deliberations are rather unsupported, because we still know very little about the representatives of Chariocrinus.…”