Samlinger Lokaliteter TidstavleFaunalister Blin


Nymphaster sp.

 Faktiske data om fund 
Katalognummer:
498
Accessionsnummer:
DK 556
Samling:
Danekræsamlingen
Samler:
Statens Naturhistorisk Museum
Finder:
Olav Foged Olsen
Bestemt af:
Lokalitet:
Mern
Stratigrafi:
Periode:
Type:
Sediment:

Billede

Foto ©: Sten Lennart Jakobsen


 Beskrivelse:   af  John W. M. Jagt 
This represents the first more or less complete specimen of the species Nymphaster spenceri (Rasmussen, 1950) to be recorded. Rasmussen (1950, p. 81, text-fig. 6c, pl. 10, figs 13, 14, as Chomataster spenceri) based this species on dissociated ossicles only, and designated holotype a proximal superomarginal (MGUH 7531) from the lower Maastrichtian of Moen. However, he (p. 81) also noted some 'associated remains of a small individual ..... from the White Chalk of Denmark. None of these finds gives the possibility of making a certain reconstruction of the animal'. The new find from Mern allows the species to be reconstructed in detail now, albeit that arm tips are poorly preserved and the actinal/abactinal and ambulacral portions are disturbed and do not show the original plating.

Within the genus Nymphaster, there appear to be have been two separate lineages. One comprises N. studlandensis, N. alseni and N. peakei (see Gale, 1987, 1989; Jagt, 2000), all three of late Campanian age (England, northeast and southern Belgium, northern Germany, France), while the other is N. rectus (=? N. humilis; Santonian-lower Campanian; England, northern Germany) and N. spenceri. Nymphaster wrighti (late Maasrichtian; Denmark, northern Germany) probably belongs to yet another group of species, being of small size and having a peculiar superomarginal ornament.

The present find is of great importance in documenting the species N. spenceri more fully and placing it in a phylogenetic context; it should be noted how close it is to the much older N. studlandensis - maybe an example of evolution with distinct lineages leading to comparable adult morphologies.

REFERENCES
Gale, A.S., 1987. Goniasteridae (Asteroidea, Echinodermata) from the Late Cretaceous of north-west Europe. 2. The Genera Calliderma, Crateraster, Nymphaster and Chomataster. -- Mesozoic Research, 1: 151-186.

Gale, A.S., 1989. Migration and evolution in Late Cretaceous Goniasteridae (Asteroidea, Echinodermata) from north-west Europe. -- Proceedings of the Geologists' Association, 100: 281-291.

Jagt, J.W.M., 2000. Late Cretaceous-Early Palaeogene echinoderms and the K/T boundary in the southeast Netherlands and northeast Belgium - Part 5. Asteroids. -- Scripta Geologica, 121: 377-503.

 Note Pighud - søstjerne - Nymphaster sp.

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