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Traumatocrinus from Guanling Biota of China: Aboral and Oral Calyx Surfaces
Biotalker posted a topic in General Fossil Discussion
There are a lot of crinoid fossils coming out of China these days, particularly this good sized and photogenic species. I believe it is called Traumatocrinus, perhaps named after a famed paleontologist who was killed during WWII. By far, most available fossils are a side view of the calyx and arms. I was interested in acquiring specimens that clearly show the echinoderm geometry on the aboral surface of the calyx. I was also interested in some view of the oral surface, which is usually hidden behind a blizzard of arms and branching pinnules. The crinoid has a pentaradial symmetry with two arms on each for a total of 10 arms. The green outline shows one of the five structures that make a five pointed "star". The oral surface is less visible. One can see plate-like structures in the center but I can't detect a mouth, hydropore or anus. -
This species is also known under the name T. hsui. The discussion about whether this is T. hsui or T. caudex seems to be still going on. Diagnosis from Hagdorn et al. 2015, p. 16: "Cup cryptodicyclic with five infrabasals and five basals; basals almost completely concealed in column pit; radials with low trapezoidal exposed aboral side and outward inclined facet with strings of granules separated by grooves (fossulae); radial articular facet and all brachial articulations ligamentary (granosyzygial). Primibrachial 2 axillary, secundibrachial 2 axillary in juveniles, in adults second arm branching after indefinite number of irregularly biserial secundibrachials. In juveniles four isotomously branching arms which constitute the 20 major arms of adults. In adults, indefinite number of endotomously branching tertiary armlets; arm branching starting at outer arms of each ray. Armlets may branch again at distal axillaries with aboral inflation or spine. Arms biserial. Brachial articulations granosyzygial with strings of granules separated by fossulae opening at equidistant circular pores along aboral sutures. Arms pinnulate after second branching. First pinnular shorter than second, with muscular articulation to brachial. Proximal and medial pinnulars with serrated margins, distal pinnulars with blade-shaped spines. Tegmen with polygonal plates, anal tube short with polygonal, aborally inflated plates around anal opening. Functional cup enlarged by means of tegminal plates extending between proximal arms, forming polygonal interbrachials and five large rhomboidal interradials inserting between interradial sutures. Interradials already present in juveniles of less than 10 mm crown height. No mouth visible; small perforated tegminal platelets at the base of free arms. Column long to very long, proximally with distinct nodals, noditaxes with up to four series of internodals. Nodals without cirri. Columnals low, circular to elliptical, granosyzygial, with multiradiate rows of granules that may be arranged as sets of chevrons; number of granule rows increasing toward the margin by bifurcation and intercalation. Intercolumnal grooves (fossulae) between granule rows with equidistant circular pore openings leading to sets of channels (tubuli) running through proximal and medial column; set of five primary tubuli surrounding lumen of central canal. Terminal column with extremely low columnals with articulated anastomosing radicular cirri, articulate facets of cirrals multiradiate." Identified by oilshale. References: Xiaofeng, W., Hagdorn, H. & Chuanshang, W. (2006 09 12) Pseudoplanktonic lifestyle of the Triassic crinoid Traumatocrinus from Southwest China. Lethaia , Vol. 39, pp. 187-193. Oslo. ISSN 0024-1164. Wang et al,. (2003) Restudy of the crinoids Traumatocrinus of the Guanling biota Guizhou. Geological Bulletin of China Vol. 22 No. 4, p. 248-253. Hagdorn, Hans; Wang, Xiao-Feng (2015). The pseudoplanktonic crinoid Traumatocrinus from the Late Triassic of Southwest China — Morphology, ontogeny, and taphonomy. Palaeoworld, (), S1871174X15000414–. doi:10.1016/j.palwor.2015.05.006
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From the album: Invertebrates
Traumatocrinus caudex Dittmar, 1866 Late Triassic Carnian Xiaowa Formation Guanling Guizhou PRC -
I was recently prepping a traumatocrinus and uncovered something I was unable to identify. There were several black, slug-like creatures entwined in the crinoid. I have prepped a lot of these plates and have never seen anything black on any of them. At first glance they appeared to be part of the crinoid, but close examination of their structure shows they do not match any part of the traumatocrinus. They are about 2" long. It's a mystery to me, but hopefully someone out there can solve it.
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