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 Triproetus tumidus

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carborges



Nombre de messages : 4
Date d'inscription : 23/06/2010

MessageSujet: Triproetus tumidus    Mer 23 Juin - 19:29

S'il vous plaît quelqu'un a une photo d'un Triproetus tumidus une trilobite le Permien?

Please someone has a picture of a trilobite Triproetus tumidus the Permian?
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TheoricienQuantique



Nombre de messages : 605
Localisation : Oxford
Date d'inscription : 15/05/2010

MessageSujet: Re: Triproetus tumidus    Mer 23 Juin - 20:41

Yep voila tu peux trouver la description complete de cette espece ici :
http://www.jstor.org/stable/1305948

Sinon la voici :
Holotype.
-A cephalon from the Skinner Ranch Formation
(Decie Ranch Member) of the Glass Mountains, USNM 447529;
locality USNM 708q, collected by G. A. Cooper and R. E. Grant.
Paratypes. -Four pygidia, USNM 447530-447532 from the
same locality as the holotype, and a complete pygidium, USNM
447528, from locality 71 lp; 10 fragmentary pygidia and three
incomplete cranidia USNM 447559 from locality USNM 708q
are not illustrated here. All specimens collected by G. A. Cooper
and R. E. Grant.
Diagnosis.
-Glabella with broadly inflated frontal lobe which
overhangs anterior margin, lateral glabellar lobes small and suboval,
pygidium with flanged border, axis and pleurae with
rounded (transverse) profile.
Description.
-Cephalon semicircular, of moderate relief and
vaulting. Glabella short, 0.77 times total cranidial length, wide
lateral expansion in frontal lobe, as wide as long, overhanging
anterior margin. Sides of glabella nearly straight, but strongly
diverging; longitudinal profile flat at posterior end, becoming
convex anteriorly; LI and L2 lateral glabellar lobes small, suboval,
furrows not evident, L3 faint to obscure. Lateral preoccipital
lobes large, inflated, triangular, preoccipital furrows narrow,
deep. Axial furrows sharp, straight between eyes, diverging in front of eyes.
Occipital furrow deep, narrow. Occipital lobe broad and flattened (axial). Facial sutures short, diverging from
g to b, long and straight from e to z. Palpebral lobes small,
crescentic, narrow (transverse). Eyes large, hemispherical; ocular
platform narrow; ocular ridge sharp, well defined. Librigenae
with short, steep section from ocular ridge to sharply rounded,
narrow, lateral border furrow. Border sharply rounded, slightly
underturned by anterior margin. Posterior border furrow sharp,
broad; genal spine very short.

Pygidium length 0.82-0.84 times maximum width, semicircular
in outline. Axis low in relief, shouldered, rounded in transverse
profile, 0.39-0.40 times maximum pygidial width, 0.90-
0.92 times total pygidial length, arched in longitudinal profile,
descending posteriorly to, but not overhanging, border at terminus,
containing 13 rings, posteriormost of which is medially
divided into two small tubercles. Ring furrows narrow, deep;
fine granules ornament apex of each ring. Pleural fields composed
of seven ribs, flattened near dorsal furrow, becoming
convex, steeply inclined, almost vertical, to border, intersecting
border at nearly right angle. Pleural furrows very deep, narrow,
reaching border. Interpleural furrows sharp, narrow. Anterior
band of each rib narrow, posterior band broader, both bands
exhibit a row of granules along posterior apex. Border well developed,
flanged, of about same width along entire margin, horizontal
adjacent to pleural fields, vertical and flat-sided, covered
with terrace lines.

Remarks.
- Triproetus tumidus n. sp. can be distinguished
from other species of this genus by a longer pygidial axis, which
is distinctly rounded in transverse profile. Triproetus subovalis
(Kobayashi and Hamada) displays a rounded pygidial profile
similar to that of T. tumidus. The cranidium of T. tumidus,
however, additionally possesses inflated lateral glabellar lobes
and a distinctly flanged pygidial border that is not rounded as
in the former species. Triproetus roemeri (von Moeller) as illustrated
by Weber (1937) differs from T. tumidus by exhibiting
a more subtrapezoidal transverse axial profile, lacking a flanged
border to the pygidium, and considerably less lateral expansion
to the frontal lobe of the glabella. Moreover, T. tumidus exhibits
inflation of lateral glabellar lobes, a character that has not been
shown for T. roemeri. Cephala of T. tumidus are strikingly similar
to those of T. altasulcus n. sp. The subtle differences will
be discussed under the latter species.

Etymology.
-"Tumidus,"' Latin for "to inflate," referring to
the laterally inflated frontal glabellar lobe.
Occurrence. -Present in the Lenox Hills Formation USNM
locality 711 c; Skinner Ranch Formation, USNM localities 705a,
707a, 708q, 711p, 726h, 733h.

Et finalement les images
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