 Famille des Proetidae (Salter, 1864) |
Crozo 
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Registration Date: 23.02.2012
Posts: 235
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 Famille des Proetidae (Salter, 1864) |
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Classification : Proetida - Proetina - Proetoidea
Représentant type de cette famille : Proetus (Steininger, 1831)
Diagnose générale de cette famille :
Cephalon : de forme généralement circulaire à semi-circulaire.
Glabelle assez volumineuse et convexe (chez proetinae), pouvant
Etre aussi rectangulaire et plate (chez les cornuproetinae), chez les (dechenellinae)
La glabelle ressemble au nez humain, avec des sillons bien marqués (comparé aux autres).
Glabelle possédant de 1 à 4 paires de sillons latéraux souvent peu marqués ; le sillon
S1 souvent très oblique scindé la glabelle en lobe (chez cyphoproetus ou perliproetus).
Chez certains genres (comme Phillibole, lepidoproetus ou certains proetus) on remarquera
L’absence de sillons glabellaire distinct.
Lobe palpébral mince, laissant la place à des yeux de belle taille en forme de croissant
Sans crêt oculaire ; Certain sont aveugle (comme diacoryphe, Drevermannia, Typhloproetus..).
Suture faciale de type «Opisthoparian»
Thorax : composé de 8 à 10 segments thoraciques. Plèvres simples avec un sillon peu profond
Terminés souvant par un bord arrondi, mais chez certains (comme Phaetonellus) les plèvres
Se prolongent en pointes assez courtes.
Pygidium : de forme semi-circulaire à rectangulaire assez trapu, avec un rachis pouvant
Etre composé de 5 à 30 anneaux et pouvant compter 14 paires de sillons inter-pleuraux.
Chez certains genres (comme Phaetonellus) les sillons se prolongent en pointes assez longues.
Répartition : de l’Ordovicien moyen au Carbonifère inférieur
Ma collection de Proetidae :
Crozo has attached these images (downsized versions):
    
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21.03.2012 08:40 |
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Crozo
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Registration Date: 23.02.2012
Posts: 235
Herkunft: Française
Thread Starter 
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21.03.2012 08:43 |
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Crozo
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Registration Date: 23.02.2012
Posts: 235
Herkunft: Française
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21.03.2012 08:44 |
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Crozo
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Registration Date: 23.02.2012
Posts: 235
Herkunft: Française
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21.03.2012 08:48 |
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Jens
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Registration Date: 18.03.2007
Posts: 2,167
Herkunft: HGW, momentan Jura, Schweiz
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Hi Hervé,
again many nice trilobites, including many rare one.
Determinations of Proetids is a hard job and especially the devonian proetids of Morocco are difficult to determinate.
By looking after your determinations I have seen, that you do not use the genus Gerastos instead of Proetus. Okay, both genera are similar but there are some clear differences.
May be I should show a specimen from my collection. Unfortunately not a real good picture, but anyway. For this specimen I'm sure, that this is a real Proetus, comes from the Wenlock of Gotland.
http://www.trilobiten.de/Pictures/view_pic.php?view=40
Compare especially the pygidium, there is a remarkable furrow visible close to the margin (on the right side bette visible). Such a forrow you will not find (or only weak developed) when you look at a Gerastos. The axis of the pygidium is broader than in Proetus and the glabella stronger inflated and tuberculated.
May be the papers from Gibb 2005 about the Proetids from Morokko is a helpfull guidance and also the work of Chatterton et al. 2006 contains some proetids.
by the way, the species Proetus akrechanus was described by Alberti, 1969 and belongs obviously to Gerastos.
As mentioned above, the correct determination of Proetids is hard, and takes time and a lot work;-)
regards,
Jens
PS: The Hamar Laghdad-Formation does not exist.
http://www.google.ch/url?sa=t&rct=j&q=ha...AdPBlMChj5tmq3g
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21.03.2012 11:25 |
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Crozo
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Registration Date: 23.02.2012
Posts: 235
Herkunft: Française
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It is true that a new determination of my proetidae is to be envisaged,
but simply I have little element to make him and the proetidae of
Morocco is sometimes very difficle. I identified my specimens with
works him of Alberti, but it is not simple.
Thank you for the advice.
by
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21.03.2012 11:57 |
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