Gnathodus cuneiformis


Sugerowana cytacja: Moczyński 2016. Gnathodus cuneiformis Mehl & Thomas 1947. Ikonoteka (http://ikonoteka.paleo.pan.pl/xwiki/bin/viewrev/Species/Gnathodus+cuneiformis)

Diagnoza

As admined by Lane et al. (1980), in early Gnathodus from their isosticha-Upper crenulata Zone there is a continuity in morphologic variability extending through all species recognised there. This applies as well to the populations from the Scaliognathus anchoralis Zone of Ostrówkq where all  morphologies corresponding to species occurring in this horizon according to Lane et al. (1980) form a single continuum morforphologies. I see no possibility at the present stage of knowledge to distinguish there any sympatric species of the genus. The variability is not only completely continuous but there is no apparent multimodality in the distribution of characters. The morphologies do not form any linear morphocline so I failed in quantifying the pattern of variability. Although the presence of several species cannot be excluded, as in any case of morphologically defined palaeontological species, I find it parsimonious not to subdivide the sample arbitrarily into more than one species, even if some future quantitative study of a better preserved and larger assemblage, or identification of the alleged 'species' in separate samples, may prove their biological validity.

All that remains in this situation is to apply a species name to this probably homogeneous series of populations in Ostrówka. No holotype of Gnathadus species comes strictly from this horizon but the closest in age seems to be that of G. cuneifurmls Mehl & Thomas, 1947 from the Fern Glen Formation at Castlewood, Missouri. The specimen, reillustrated by Lane et al. {1980: pl. 10: 7) is a juvenile with no specific characters, but there is no reason to suspect that its population was different from that from Osrówka, although the Fern Glen Formation is somewhat older than the Radlin beds. The same applies to the horizon 14.9 m above base of the Lake Valley Formation in Dog Canyon of New Mexico, from where the type series of Protognathodus cordifurmis Lane, Sandberg , &Ziegler, 1980 comes. It is associated with specimens classified by Lane et al. (1980) as Gnathodus cuneifurmis (early) and G. delicatus. Scaliognathus praeanchoralrs dates the horizon.

Another possible name-bearer is the type of G. pseudosemiglaber Thompson & Fellows, 1970 from the Reeds Spring Formation at the Tahlequah North section of Oklahoma, where the conodont assemblage is clearly monospecific. Probably in populational terms these populations are conspecific. The Gnathodus typicus Cooper, 1939 type series comes from the same stratum as G. punctatas Cooper, 1939 and both may be reworked from older strata of unspecified age. G. semiglaber Bischoff,1939 comes from a horizon younger than that in Ostrówka.

Porównanie

Autekologia

Występowanie geograficzne

Zasięg czasowy

Materiały muzealne

Literatura

Dzik, J. 1997. Emergence and succession of Carboniferous conodont and ammonoid communities in the Polish part of the Variscan sea. Acta Palaeontologica Polonica 42, 57-170.

Specyfikacja

Królestwo
ANIMALIA 

Typ
CHORDATA 

Podtyp
CONODONTA

Gromada
CONODONTOPHORIDA

Podgromada
EUCONODONTA

Rząd
Ozarkodinida

Podrząd
Ozarkodinina

Rodzina
Idiognathodontidae

Rodzaj
Gnathodus

Gatunek
Gnathodus cuneiformis

Synonimy

Populacja typowa gatunku

Holotyp

Locus typicus

Stratum typicum


Tags:
Created by Administrator on 2016/07/11 15:36

This wiki is licensed under a Creative Commons 2.0 license
XWiki Enterprise 6.4.8 - Documentation