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Northamerican archaic skulls and mandibles
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Preorbital Fossa : one possible cause (Remarks)
lundi 28 janvier 2013
par Véra Eisenmann
Many explanations have been proposed for the function(s) of the POFs. In Equus at least, one possible cause (not "function") is the "caveing-in" of the malar region when it is no more "sustained" by cheek teeth because they are too worn.
As example, here is the skull of an E. caballus found (...) > suite
Comparisons with Old World Hipparions (Remarks)
Thursday 3 June 2010
by Véra Eisenmann
The scatter diagram SD-6 shows that (as far as I know) all Old World Hipparion skulls belong to Group B except H. prostylum (Lubéron LY 592) which has the same proportions as Group A-8 ( Ratio diagram A-8 and H. prostylum).
H. hendeyi (Langebaanweg E 22187), although larger, resembles (...) > continue
Chronology (Remarks)
Thursday 3 June 2010
by Véra Eisenmann
From the chronology of the sites (probably outdated table), it appears that the Group A is very old: Thomson, Echo Quarry, Trinity River. Even the brachyodont Mesohippus, Miohippus (Meso-Mio), Hypohippus, Megahippus and Parahippus (Hypo-Mega-Para) have the same shortness of the naso-incisival (...) > continue
Correlation between length of upper P2-M3 and size of the bar (32) (Remarks)
Wednesday 2 June 2010
by Véra Eisenmann
The correlation between length of the cheek teeth P2-M3 and preorbital bar length (Scatter diagram 5) does not follow the same regression line for Cormohipparion (all morphs) and other archaic Northamerican equids. > continue
Lack of relation between the main axial skull proportions and the pre-orbital bar (Remarks)
Wednesday 2 June 2010
by Véra Eisenmann
It seems that the main axial proportions of the skull are independent from the existence and/or type of POF.
For instance, on the ratio diagram of Cormohipparion A (A-1), the skull 42449 from Kepler looks like a typical Cormohipparion A although it has no POF.
The ratio diagram A-2 shows (...) > continue
Skull proportions and size of the pre-orbital bar (Size of Pre-orbital bar (32))
lundi 31 mai 2010
par Véra Eisenmann
Skull proportions and size of the preorbital bar (32)
1. Compared to many other ancient Northamerican equids (SD-2) Scatter diagram 2, all ‘typical’ Cormohipparion A and B (morphs 1) have a longer bar (32) relative to the length of the NIN (30).
2. The separations is, however, not so sharp (...) > suite
Skull proportions, excluding the size of the preorbital ‘bar’ (32) : Unclassified (Ratio diagrams, 8 variables)
lundi 31 mai 2010
par Véra Eisenmann
Unclassified.
Five skulls remain unclassified using this kind of ratio diagram (Unclassified 1).
Unclassified fragments. Fifteen other skulls were too fragmentary to be studied by this kind of ratio diagram (Unclassified 2). > suite
Skull proportions, excluding the size of the preorbital ‘bar’ (32) : Miohippus & Mesohippus (Ratio diagrams, 8 variables)
lundi 31 mai 2010
par Véra Eisenmann
Skull proportions, excluding the size of the preorbital ‘bar’ (32) : Hypo, Mega, & Parahippus (Ratio diagrams, 8 variables)
lundi 31 mai 2010
par Véra Eisenmann
Skull proportions, excluding the size of the preorbital ‘bar’ (32) : Dinohippus & Pliohippus (Ratio diagrams, 8 variables)
lundi 31 mai 2010
par Véra Eisenmann
Dinohippus and Pliohippus
Dinohippus 11724, 87201, and Pliohippus 12998 have similar proportions (Dino-Plio 1) but only the last one has a well developped POF.
Five other skulls are all different (Dino-Plio 2). > suite
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Equidae tridactyles (Hipparions sensu lato)
Northamerican archaic skulls and mandibles
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