某Prionitidae

2023-04-12 23:23 作者:从冥古宙走来 0人读过 | 我要投稿

以下图示可能是米克菊石，但由于缝合线与模式标本有些差异（可能是壳体较小齿未发育出来），故暂时将其视为锯齿菊石（Prionitidae）

Prionitidae Hyatt,1900 锯齿菊石科

MEEKOCERAS Hyatt,1879

The genus Meekoceras was previously included in the family Meekoceratidae Waagen，1895 (Tozer,1994). Apart from Meekoceras of middle Smithian age,this family contains only Dienerian genera (e.g. Arnbites,Gyronites,Meekophiceras, Pleurambites, Pleurogyronites andPrionolobus). On the other hand, Meekoceras shares the following important characters with Prionitidae: a compressed whorl shape (e.g. like Prionites nammalensis sp.nov.), a suture line with low, broad saddles, and an umbilicus with an inclined wall. On the basis of these similarities, Meekoceras is herein assigned to Prionitidae, and the family Meekoceratidae is herein no longer regarded as a valid taxon. The Dienerian genera that have been included in Meekoceratidae are herein treated as members of the family Gyronitidae Waagen, 1895, Typical members of Gyronitidae differ from typical Prionitidae by their more evolute, platyconic shell with a tabulate venter. Any possible phylogenetic relationship between the Dienerian Gyronitidae and the middle-late Smithian Prionitidae has yet to be established. Their superficial similarities are here interpreted as the result of convergence.

A-W,Meekoceras cf. gracilitatis White, 1879. A-B, PIMUZ 28085; x0.9. From sample Chil05, Chiddru. C-F,PIMUZ28086; X0.9.G-H,PIMUZ 28087; 0,9.1-L, PIMUZ 28088. M-0, PIMUZ 28089. P-R,PIMUZ 28090; Q-R 2. S-W,PIMUZ 28091;S x2, at D = 19 mm, H = 9,3 mm. ll except l-2 from sample Nam18, Nammal. All from the Nammalites pilatoides beds, Upper
Ceratite Limestone. All natural size unless otherwise indicated.

PRIONITIDAE Hyatt,1900

PRIONITES Waagen，1895

Type species. Prionites tuberculatus Waagen, 1895.

Prionites tuberculatus Waagen, 1895

描述：Involute shell with eggressive coiling at maturity Maximum whorl width at upper third of flank. Venter tabulate with angular shoulders on inner whorls, subtabulate with rounded shoulders on outer whorls, Umbilicus deep and funnel-shaped with inclined wall and rounded shoulders. Inner whorls smooth, outer whorls with prorsiradiate, distant bullae on inner flank that develop into strong, broad tubercles on some specimens. Growth lines biconcave. Suture line ceratitic with broad saddles; third lateral saddle very low.

属于诺利菊石科的诺利菊石属与该青海菊石挺像，其描述为：壳体内卷，呈板状，在平板状的腹部上具有腹侧缘脊。以此与锯齿菊石相区别。

PARANORITES Waagen, 1895 副诺利菊石属

Type species. Paranorites ambiensis Waagen, 1895.

Paranorites ambiensis Waagen，1895

Very large, moderately involute, compressed shell with convex,convergent flanks. Venter tabulate with subangular shoulders. Umbilicus with high vertical wall and marked, slightly rounded shoulders. Ornamentation consists of distant, low folds that are most prominent near the umbilicus and fade out towards the venter. Additionally, fine blunt spiral lines are visible on the flanks. Suture line with strongly indented, deep lobes; first lateral saddle distinctly phylloid; second lateral saddle slightly phylloid and tapered; third lateral saddle flattened; auxiliary series relatively long with well-individualized small saddles.

参考：Brühwiler, Thomas & Bucher, Hugo & Ware, David & HERMANN, ELKE & Hochuli, Peter & Roohi, Dr. Ghazala & Rehman†, Khalil. (2010). Smithian (Early Triassic) ammonoids from the Salt Range, Pakistan. Paleontology. special paper. 1-226. 10.5167/uzh-67428.