Treveropyge maura

 

Very rare Devonian Trilobite from Morocco, this trilobite has been recently described by Pierre Morzadec 2001, from a single specimen, in : " Les trilobites Asteropyginae du dévonien de L'Anti-Atlas" (Paleontographica Abt.A, 262 (1 - 3) : pp 53 - 85). I heartily thank Mr Renato Rinaldi who identified this bug for me when I couldn't access that Morzadec's publication.

This specimen is a sad example of the "Moroccan" preparation, though, with its white lines radiating from the bug. These lines make the trilobite analysis tiring and difficult, and moreover, they usually draw borders that are not the exact ones, notably to the spines... and here to the cephalic border (cf. infra).

I present in the second part of the page Treveropyge berbera MORZADEC 2001 to help in an appropriate diagnose.

2001 Treveropyge maura nov. sp., MORZADEC 2001, p.72, planche 10, fig. 1.

 

Specimen description :

  • Complete trilobite.
  • On matrix
  • Positive and a part of negative.
  • Perfect eyes.
  • Multiple granulations on the exosqueletton.
  • Strongly 3D.
  • Slight disarticulation of the pygidium.
  • Total size : 96 mm
  • Devonian - Upper Emsian.
  • Morocco.

 

Complete view of the specimen.
Part ot the negative and lateral view.

 

Diagnosis :

 

Order

 

 

 

 

 

 

 

 

 

Phacopida

 

 

 

 

 

 

 

 

 

SALTER 1864

 

 

 

 

 

 

 

 

 

Occurrence: Lower Ordovician (Tremadoc) to Upper Devonian (Famennian).

  • Cephalon: Proparian (Phacopina and Cheirurina), gonatoparian (Calymenina) or opisthoparian (Calymenina),
  • Preglabellar field often very short or absent.
  • 4 or fewer pairs of glabellar furrows.
  • Eyes : when present, schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina).
  • With rostral plates (Calymenina and Cheirurina) or without (some Phacopina).
  • Hypostome conterminant (all suborders) to impendent (some devonian Phacopina).
  • Exosqueletton generally granulous.
  • Thorax: 8 – 19 segments, sometimes distinctly furrowed.
  • Axis sometimes broad (e.g., Homalonotidae).
  • Pygidium : Typically micropygous (most Calymenina and Phacopina), but variable (e.g., subisopygous in Dalmanitoidea and Acastoidea).
  • May be lobed or spiny (e.g., Cheirurina, some Dalmanitoidea, Acastoidea), or smooth-margined, with round or subtriangular outline (e.g., Calymenina, Phacopoidea).

Sub-order

 

 

 

 

 

Phacopina

 

 

 

 

 

STRUVE 1959

 

 

 

 

 
  • Cephalon : Proparian sutures (sometimes fused).
  • Schizochroal eyes.
  • Glabella expands forwards.
  • Librigena typically yoked as single piece.
  • Hypostome conterminant to impendent, some with no rostral plate.
  • Some with genal spines.
  • Thorax: 10 to (typically) 11 segments.
  • Pleurae furrowed, articulating facets distinct.
  • Rounded, angular, or spinose tips.
  • Pygidium : Typically smaller than cephalon (but subisopygous in Dalmanitoidea and Acastoidea).
  • Smooth or spinose.

Super-family

 

 

Acastoiedea

 

 

DELO 1935

 

 
  • Cephalon : Axial furrows slightly to moderately divergent.
  • Anterior glabellar lobes and furrows usually not fused (although furrows may be indistinct).
  • Eyes typically distant from posterior border furrows, but not strongly anterior.
  • Frontal glabellar lobe auxilliary impression system triangular in outline.
  • Maximum width of glabella adjacent to preglabellar furrow.
  • Median region of glabella devoid of muscle scars.
  • Cephalic margin "shouldered".
  • Laterally convex course of genal margin topographically distinct from curvature of axial margin.
  • Thorax : Pleural endings blunt, rounded or angular.
  • Sometimes spinose.
  • Pygidium : Micropygous to subisopygous.
  • Sometimes spinose (expressed as marginal spines).
  • Pygidial axis with deep, apodemal anterior ring furrows, with abrupt transition to shallow posterior ring furrows.
  • Coincident decrease in angle of axial furrow convergence.

Family

 

 

 

 

 

Acastidae

 

 

 

EDGECOMBE 1993

 

 

 

 
  • Cephalon : Semi-circular to rounded subtriangular.
  • Cephalic border narrow in front of the glabella.
  • Dorsal furrows slilghtly to moderately divergent.
  • Anterior glabellar furrows (S3) simple.
  • Medial furrows (S2) moderately deep.
  • Deep posterior furrows (S1).
  • L2 and L3 lateral glabellar lobes generally fused distally.
  • Muscle scars bearing sometimes callosities (Acastinae).
  • Eyes typically distant from the posterior genal furrows.
  • Hypostoma
  • Pygidium : micropygous to subisopygous.
  • Semi-circular to rounded subtriangular.
  • Short posterior spine present.

Sub-family

 Asteropyginae

DELO 1935

Traditionnally included in the Dalmanitidae, Asteropyginae are now included in the Acastids. Mostly benthic trilobites.

  • Cephalon : Closely similar to the Dalamanatid Dalmanitides BARRANDE 1853.
  • Glabella expanding forward.
  • 3 lateral glabellar furrows.
  • Eyes generally large.
  • Genal angles acutely pointed or bearing medium-length to very long genal spines in straight continuation of lateral margins.
  • Pygidium : Rachis never reaching the posterior region of the pygidial border.
  • Generally 5 pairs of lateral spines (sometimes 4 or 6).
  • Unpaired posterior lappet or spine.

Genus

 

Treveropyge (Treveropyge)

STRUVE 1958
  • Cephalon : Subparallel dorsal furrows.
  • Glabella with depressed median area.
  • Abaxially fused glabellar lobes L2 and L3.
  • Large convex eyes.
  • Very broad genal angles.
  • pygidium : Broad rachis.
  • Segmentation of "prorotundifrons" type

Species

maura

MORZADEC 2001
  • Cephalon : 3 times wider than long.
  • Large visual surface with 31 dorso-ventral rows of lenses.
  • Pygidium : Large.
  • 17 axial rings.
  • 8 pairs of pleural ribs.
  • Lateral pygidial spines as long as the corresponding rib.
  • Median pygidial spine very broad and short.

Description :

Complementarily to the diagnosis, one can precise the following points :

Discussion :

Treveropyge berbera differs from Treveropyge maura by a cephalon 2 times wider than long, with a short anterior point. 34 dorso-ventral rows of lenses with 13 lenses maximum per row. Thoracic rachis larger. 12 pygidial axial rings, without tubercles pairs. Pygidial spines flat and short. Median spine shorter than the lateral spines.

Complementary pictures :

Cephalon :
Left eye.
Right facial suture.
Cephalic granulation.
larger granulations, under the exosqueletton.
Counting of the dorso-ventral rows of lenses

The cephalon presents parts that show exfolliation, revealing granulations different in size and sometimes letting sutures or structures being better shown (see the posterior section of the facial suture).

The problematic anterior border of the cephalon...

The anterior border is supposed to be wedge-shaped, but the prep work did make things unsure there. one can't really say where the exact anterior border is...

"Doubtfull outline"...

"more realistic anterior border"

Scroll over the picture....

 

The thorax :

It presents remarkable pair of granulations on the axial rings that will be found on the pygidium too.

The distal extremity of the pleurae is spinose.

 
Dorsal view of the axial rings. Note the pair of granulations.
Detail of the spinose tips.

 

The pygidium :

 

Prorotundifrons-type segmentation.
Triangular pygidium.

 

Short median spine.
Limit (white line) between the probably real end and the "restorated" one.

Scroll over the picture....

 

Holotypes :

1 - Treveropyge maura :

 

Lateral view. Complete exosqueletton. Holotype. Coll. P. CATTO. (After Morzadec, 2001).

Frontal view. Complete exosqueletton. Holotype. Coll. P. CATTO. (After Morzadec, 2001).

 

Dorsal view of the cephalon Holotype. Coll. P. CATTO. (After Morzadec, 2001).

Dorsal view of the pygidium. Holotype. Coll. P. CATTO. (After Morzadec, 2001).

 

2 - Treveropyge berbera :

 

Dorsal view of the cephalon. Complete exosqueletton. Holotype. Coll. P. CATTO. (After Morzadec, 2001).

Frontal view. Holotype. Coll. P. CATTO. (After Morzadec, 2001).

 

Dorsal view of the pygidium. Holotype. Coll. P. CATTO. (After Morzadec, 2001).

References :

MORZADEC P. 2001. Les Trilobites Asteropyginae du Dévonien de l'Anti-Atlas (Maroc) [Asteropyginae Trilobites from the Devonian of the Anti-Atlas (Morocco)]. Paleontograph. Abt. A 262 (1/3) : pp 53 - 85.

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