Primozygodactylus major Mayr, 1998
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publication ID |
https://doi.org/ 10.4202/app.2009.B103 |
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persistent identifier |
https://treatment.plazi.org/id/03BF87AF-FF98-FFBE-FF5B-BE0CAD08F833 |
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treatment provided by |
Felipe |
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scientific name |
Primozygodactylus major Mayr, 1998 |
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Primozygodactylus major Mayr, 1998
Fig. 3 View Fig .
Referred specimen: SMF−ME 799a+b, incomplete and dissociated skeleton lacking left wing, left tarsometatarsus, and pelvis.
Locality and horizon: Messel near Darmstadt, Hessen, Germany; early middle Eocene, MP 11 ( Legendre and Lévêque 1997) .
Measurements.—See Table 1.
Description and comparisons.—The vertebral column is largely dissociated, which allows the recognition of previously unknown features of some particular vertebrae. The atlas and axis are preserved in articulation, and it can be discerned that the former had a dorsally open incisura fossae ( Fig. 3A View Fig 1 View Fig ). Contrary to the statement in the description of the holotype ( Mayr 1998), the foramen enclosed by the arcus interzygapophysialis (terminology after Livezey and Zusi 2006) of the fourth vertebra is large as in most passeriform birds ( Fig. 3A View Fig 2 View Fig ).
In the new specimen, the coracoid of a Messel representative of Primozygodactylus is for the first time fully visible. The processus acrocoracoideus is dorsoventrally compressed, with a rounded tip, and is proportionally shorter and stouter than the narrow and elongate processus acrocoracoideus of Zygodactylus . The processus procoracoideus is very small. In contrast to crown group Piciformes ( Mayr et al. 2003), there is no notch in the medial margin of the extremitas sternalis, which instead bears a distinct convex flange. The processus lateralis is longer than in Zygodactylus , whose extremitas sternalis is much narrower ( Fig. 3 View Fig ). The completely exposed furcula allows the recognition of a long processus acromialis on the extremitas omalis, and a well−developed, blade−like apophysis furculae on the extremitas sternalis ( Fig. 3A 3 View Fig ). As noted in the original description of the species ( Mayr 1998), the scapula of P. major has a massive acromion.
The wing bones do not show features that were not already described by Mayr (1998). The processus craniolaterales of the sternum are wide and of triangular shape.
The distal end of the tarsometatarsus is visible in plantar view in SMF−ME 799a. The trochlea metatarsi II is very small and divided into two rims which are separated by a shallow furrow; whether the medial rim bore a plantarly directed projection cannot be discerned since the corresponding area is broken. As in P. eunjooae , the trochlea metatarsi III is asymmetric, as is the proximal phalanx of the third toe. The trochlea metatarsi IV bears a large trochlea accessoria whose original shape, however, cannot be determined. This trochlea seems to have been slightly shorter than the trochlea metatarsi II ( Fig. 3 View Fig ). Again, the phalanges of the second toe are much thinner than those of the third and fourth toes.
In the area of the cervical vertebrae grit is preserved (SMF−ME 799b) which probably represents content of the former crop. Also in SMF−ME 799b, stomach contents are preserved and include the remains of seeds.
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