Procolophonidae, Lydekker, 1889
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publication ID |
https://doi.org/ 10.4202/app.01109.2023 |
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persistent identifier |
https://treatment.plazi.org/id/03A9A05D-FFEB-2033-FF19-F931BAC5F930 |
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treatment provided by |
Felipe |
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scientific name |
Procolophonidae |
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Procolophonidae gen. et sp. indet.
Fig. 4B View Fig .
Material.—ZPAL V. 78/1, maxilla with broken posterior part from lower Olenekian (Lower Triassic) of Stryczowice, north-eastern margin of the Holy Cross Mountains, Poland.
Description.—Maxilla (ZPAL V. 78/1) is broken into two parts embedded in rock matrix, one preserving most of the bone and three teeth, whereas the other has three teeth and the posterior piece of the same bone ( Fig. 4B View Fig ). The lateral surface of the bone is poorly preserved and provides little anatomical information. The lateral surface is flat with no visible postnarial maxillary depression. The maxillary foramen opens anteroventrally near the ventral margin of the bone and near the facet for the premaxilla. The facet is well preserved and oriented anteromedially, although it is still partially covered by sediment. This anterior margin of the bone is blunt and dorsoventrally tall. There is no emargination for the naris. The bone is anteroposteriorly straight and labiolingually broad in ventral view. The posterior aspect of the maxilla is broken and incomplete.
The teeth are visible only in lateral view and in cross-section, which limits their description to some extent. The preserved portion of the maxilla bears ten tooth positions, but only six teeth remain in place (4 th to 8 th, and 10 th maxillary teeth). All teeth are subtriangular in lateral view with broad bases ( Fig. 4 View Fig ). Their tips are rather blunt, but it is not visible due to rock matrix if they have one or two cusps. The teeth gradually increase in size posteriorly up to seventh tooth, but the differences are modest. The enamel has a rather featureless surface, with no visible grooves or other structures. The first tooth was virtually circular in cross-section (orthogonal diameters of 0.88 mm vs 0.89 mm). The following teeth gradually increase in labiolingual breath, which becomes much larger than their mesiodistal length. The sixth tooth is the posteriormost one for which the measurement is possible. It is 1.63 mm wide labiolingually and 1.16mm long mesiodis- tally. After the seventh tooth they seem to slightly decrease in size but the rock matrix precludes exact measurements.
Remarks.—Up to four different procolophonids were described from roughly coeval (Olenekian) paleokarst bone breccia recovered from the Czatkowice 1 site ( Borsuk-Białynicka and Lubka 2009). Procolophonids found there have much lower maxillary tooth counts (5–6 and 7), and the teeth are more heterodont in size compared to those from Stryczowice. Procolina teresae Borsuk-Białynicka & Lubka, 2009 , has a much more pronounced anterior slope of the maxilla and its teeth are less triangular. The latter is also true for Procolophonidae gen. indet. II and III from Czatkowice 1. Procolophonidae gen. indet. I from Czatkowice 1 has subcircular teeth in cross-section throughout the entire maxilla, whereas the Stryczowice specimen has transversely expanded the posterior teeth. Therefore we can exclude assignment of the new material to any of the taxa from Czatkowice 1.
Numerous other procolophonids were described from the Buntsandstein of Germany ( Huene 1912; Säilä 2008; Sues and Reisz 2008). The Stryczowice material cannot be assigned to Sclerosaurus armatus Meyer in Fischer, 1857, because the latter has a lower tooth count (7) and its teeth have long-axes oriented mesiolingually ( Sues and Reisz 2008) rather than lingually. The comparison to Anomoidon liliensterni Huene, 1939 , is fairly limited due to its poorly preserved maxillae ( Säilä 2008), but the teeth seem to be much more heterodont in terms of size compared to the Stryczowice material. Koiloskiosaurus coburgensis Huene, 1912 , has a similar tooth count (9 or 10) in the maxilla and its teeth are expanded transversely ( Huene 1912) as in the Stryczowice material.
Procolophonids are also very diverse in the Lower Triassic of Russia ( Ivakhnenko 1979; Ivakhnenko and Kurochkin 2008; Spencer and Benton 2000). The specimen from Stryczowice differs from specimens assigned to species of Tichvinskia , Orenburgia , and Kapes in having a higher tooth count ( Ivakhnenko 1973, 1975, 1983; Spencer and Benton 2000). Phaanthosaurus (= Contritosaurus ) has 10 rather uni- form teeth in its maxilla but also possesses a large fossa surrounding the external naris ( Ivakhnenko 1974, 1979; Spencer and Benton 2000). The latter feature seems to be absent in the Stryczowice specimen.
To sum up, the Stryczowice material can be distinguished from all species mentioned above except maybe Koiloskiosaurus coburgensis Huene, 1912 , described from the Buntsandstein of Germany. However, more detailed comparisons between the two are difficult as the material of Koiloskiosaurus coburgensis requires redescription ( Sues and Reisz 2008) and we did not study these specimens per- sonally. Therefore, their possible conspecificity requires further study.
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