Martinelli et al.—Procolophonians in the German Middle Triassic
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Figure 4. Selected muscles mentioned in text for the humerus SMNS 92101 in (1) dorsal and (2) ventral views. Muscle data obtained from Romer (1922, 1956), Holmes (1977), and Angielczyk et al. (2009). Dark gray indicates muscle origin; light gray indicates muscle insertion.
Systematic paleontology
Anatomical abbreviations.—A, crest ‘A’; B, crest ‘B’; bb, bro- ken bone; ca, capitellum (radial condyle); dpc, deltopectoral crest; bpr, buttress process; ect, ectepicondyle; ectn, ectepi- condylar notch; ent, entepicondyle; entf, entepicondylar fora- men; h, humeral head; lt, lesser tuberosity; sp, supinator process; tr, trochlea (ulnar condyle).
Subclass Parareptilia Olson, 1947 Suborder Procolophonia Seeley, 1888
Superfamily Procolophonoidea Romer, 1956 Family Owenettidae Broom, 1939 Aff. Barasaurus Piveteau, 1955 Figures 1, 2
Referred specimens.—SMNS 92101, left humerus (Fig. 1); SMNS 92100, right humerus, heavily crushed (Fig. 2).
Occurrence.—SMNS 92101 comes from the Kupferzell local- ity, Germany. SMNS 92100 comes from the Schumann quarry (near the village of Eschenau), Germany. Middle Triassic Erfurt Formation (lower Keuper, Ladinian).
Remarks.—Barasaurus besairiei Piveteau, 1955 is the only species of the genus (Piveteau, 1955). It is based on several specimens (unpublished data, Meckert, 1995) from the upper Permian of lower Sakamena Formation, cropping out in Rano- hira, southern Madagascar. Subsequently, the genus was recor- ded in the Lower Triassic middle Sakamena Formation (Madagascar; Ketchum and Barret, 2004), which, according to faunal and palynological comparisons, is considered to be intermediate in age between the Lystrosaurus and Cynognathus Assemblage Zones of South Africa (Battail et al., 1987;
Ketchum and Barret, 2004). Both humeri described here are referred to Owenettidae, aff. Barasaurus, because they have the same humeral morphology as Barasaurus (with a combination of features different from any other known amniotes; see description and comparisons, and Fig. 5) and a diagnostic fea- ture (i.e., lack of an ectepicondylar foramen) for the family Owenettidae (sensu Reisz and Scott, 2002). Nonetheless, because the German specimens represent a stratigraphically younger record (Middle Triassic) and come from distant local- ities, the taxonomic assignment should be considered tentative.
Description.—The material referred to Owenettidae, aff. Barasaurus, consists of two isolated humeri that represent a single morphotype, with slight differences between them (Figs. 1, 2). These differences could be explained by ontogeny (SMNS 92101 is about 25% smaller —considering the total length—than SMNS 92100; see Table 1), taphonomy (SMNS 92101 is better preserved, being unaffected by compression unlike SMNS 92100), and that they come from different local- ities but from the same horizon.
SMNS 92101.—The specimen is a left complete humerus (see Table 1). The humerus is stout with well-defined processes and a well-preserved external surface, and considering its small size, its robustness and processes are noteworthy (Fig. 1). Its prox- imal and distal ends are expanded and twisted relative to one another. The angle between the axis of the proximal articular end relative to the transverse width axis of the distal end is 63°. The maximum proximal width (from the anterior end of the deltopectoral crest to the posterior end of the lesser tuberosity) equals 44% of the maximum length, whereas the maximum preserved width, between the epicondyles, represents 48%. The proximal articular surface is dorsoventrally elongated and drop shaped. A more rounded surface, which should
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