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Echinoidea source details

Kroh, A., Lukeneder, A. & Gallemí, J. 2014. Absurdaster, a new genus of basal atelostomate from the Early Cretaceous of Europe and its phylogenetic position. Cretaceous Research 48, 235–249.
175162
10.1016/j.cretres.2013.11.013 [view]
Kroh, A.; Lukeneder, A.; Gallem?, J.
2014
Absurdaster, a new genus of basal atelostomate from the Early Cretaceous of Europe and its phylogenetic position
Cretaceous Research
48, 235-249
Publication
Field work in the Lower Cretaceous of the Dolomites (Italy) has resulted in the recovery of a new genus of ‘disasteroid’ echinoid, which successively was also discovered in slightly older strata in Northern Hungary. This new genus, Absurdaster, is characterized by its highly modified, disjunct apical disc in which all genital plate except genital plate 2 are reduced or fused. The gonopores (which may be multiple) have shifted and pierce interambulacral plates. Anteriorly ambulacrum III is distinctly sunken and forms a distinct frontal notch, while the posterior end is pointed and features a small sharply defined posterior face bearing the periproct. Two new species are established: Absurdaster puezensis sp. nov. from the Upper Hauterivian to Lower Barremian Puez Formation of Northern Italy is characterized by its rudimentary ambulacral pores in the paired ambulacra, high hexagonal ambulacral plates aborally and multiple gonopores in the most adapical plates of interambulacral columns 1b and 4a. Absurdaster hungaricus sp. nov. from the Lower Hauterivian Bersek Marl Formation of Northern Hungary, in contrast, shows circumflexed ambulacral pores, low ambulacral plates, a single gonopore each in the most adapical plates of interambulacral columns 1b and 4a and a flaring posterior end, with sharp margin and invaginated periproct. In addition to those two species Collyrites meriani Ooster, 1865 from the uppermost Berriasian to basal Barremian of Switzerland is attributed to the new genus. Despite the poor knowledge on this form it seems to be distinguished from the new species by its smaller ambulacral plates and higher interambulacral/ambulacral plate ratio. Phylogenetic analyses based on previous work by Barras (2007) and Saucède et al. (2007) indicate that the new genus is a highly derived stem-group member of the Atelostomata close to the split of holasteroids and spatangoids. A combined analysis based on a subset of the characters employed in these two studies for the first time results in a fully resolved tree for ‘disasteroids’. Absurdaster, shows two notable morphological peculiarities: 1) it is one of the first echinoids to develop fascioles and exhibits a yet unknown type of fasciole circling the periproct, termed circumanal fasciole here; 2) it is extraordinary among echinoderms as its extraxial skeleton is reduced to a single plate, the madreporite (genital plate 2), and because its genital pores pierce axial elements rather than extraxial ones.
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2014-02-24 15:33:05Z
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 Diagnosis

Collyritid with highly modified, disjunct apical disc in which only genital plate 2 is retained and forms a ... [details]

 Diagnosis

An Absurdaster species with circumflexed pores and low plates in the ambital part of the anterior paired ambulacra; ... [details]

 Diagnosis

An Absurdaster species with numerous small, hexagonal plates in the supraambital part of the anterior paired ... [details]

 Diagnosis

An Absurdaster species with rudimentary pores and large, high, hexagonal plates in the aboral and ambital part of ... [details]

 Etymology

Referring to the puzzling morphology exhibited by the type-species. [details]

 Etymology

Referring to the country of origin. [details]

 Etymology

Referring to the type locality. [details]

 Stratigraphy

Bersek Marl Formation, Lower Hauterivian, Acanthodiscus radiatus Zone. [details]

 Stratigraphy

“Néocomien-Urgonien” of Ooster (1865: p. 58). The Veveyse outcrop encompasses sediments from uppermost ... [details]

 Stratigraphy

Puez Limestone Member of the Puez Formation; Upper Hauterivian “Pseudothurmannia ohmi” Zone (Pseudothurmannia ... [details]

 Type locality

Bersek Quarry, Lábatlan, Komárom-Esztergom county, Hungary (Gerecse Mountains, Transdanubian Range) [details]

 Type locality

Valley of the Veveyse River, Fribourg, Switzerland. [details]

 Type locality

southern side of Piz de Puez, Puez-Odle-Gardenaccia Plateau, Dolomites, about 30 km northeast of Bozen, Italy [details]

 Type material

Holotype: Hungarian Natural History Museum HNHM PAL 2013.30.1. Paratypes: Hungarian Natural History Museum HNHM PAL ... [details]

 Type material

Holotype: Naturhistorisches Museum der Bürgergemeinde Bern NHMBE 5015015 (Ooster, 1865: pl. 9, fig. 10; from ... [details]

 Type material

Holotype: Naturmuseum Südtirol STMN PZO 341 (CP172). Paratypes: Museum de Gherdëina MG P-257, Naturhistorisches ... [details]


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