EAVP 2021: Tridentinosaurus soft tissues

From the Rossi et al. 2021 abstract:
“Tridentinosaurus antiquus Leonardi 1959 is a nearly complete reptile-like tetrapod (possibly a member of the Protorosauria group) found in the Early Permian volcanic succession in Trentino Alto Adige, Italy.”

Possibly? Let’s not guess. Let’s find out what it is. In the large reptile tree (LRT, 1890+ taxa) Tridentinosaurus nests far from Protorosaurus, at the base of the Lepidosauriformes, at the base of the pseudo-rib gliding clade (Fig. 2).

Figure 1. Tridentinosaurus at 26.5 cm long is an Earliest Permian ancestor to Late Permian Coelurosauravus and Late Triassic Icarosaurus.
Figure 1. Tridentinosaurus at 26.5 cm long is an Earliest Permian ancestor to Late Permian Coelurosauravus and Late Triassic Icarosaurus.

From the Rossi et al. 2021 abstract:
“Its phylogenetic position is currently uncertain.”

See above. Don’t be lazy. A valid phylogenetic context is essential and, by their own admission, missing from this abstract.

Figure 2. Derived lepidosauriformes. The clade Pseudoribia includes the pseudo-rib gliders
Figure 2. Derived lepidosauriformes. The clade Pseudoribia includes the pseudo-rib gliders

The abstract continues:
“Soft tissues are reported in this specimen but their nature remains unclear. The specimen shows a defined black coloured body outline, alluding that most of the soft tissues are organically preserved. In the proximity of the shoulder and pelvic girdle, three-dimensionally preserved integumentary scales are evident; these are relatively small (ca. 1 x 2 mm) and rhomboidal in shape. Our study reveals that the integumentary scales are in fact osteoderms, formed by apatite with a pitted texture; no ultrastructure of the integument is preserved. The body outline and the abdomen are formed by anhedral crystals of apatite coupled with a small amount of carbon.”

And now, the kicker:
“We suggest that the body outline and the abdomen have been covered with a layer of black paint (e.g., Bone Black) perhaps to consolidate/protect the specimen. Our findings indicate the absence of soft tissues preserved in T. antiquus but the discovery of small rhomboidal osteoderms uncovers a new biological character that will support future phylogenetic studies of this ancient tetrapod.”

Future? There is a current online phylogenetic study (Fig. 2) into which Tridentinosaurus was added based on bone traits (not soft tissue outlines) back in 2016.

Tridentinosaurus antiquus 
(Early Permian, Dal Piaz 1932, Leonardi 1959, 26.5cm long; Museum of Paleontology of the University of Padua 26567). Ronchi et al. described the specimen as “a beautiful but biochronologically useless specimen of which only the out−line of the soft tissues is well preserved.” The volcanic sediments in Sardinia occur in Cisuralian / Sakmarian deposits 291 million years old.


References
Dal Piaz Gb. 1932 (1931). Scoperta degli avanzi di un rettile (lacertide) nei tufi compresi entro i porfidi quarziferi permiani del Trentino. Atti Soc. Ital. Progr. Scienze, XX Riunione, v. 2, pp. 280-281. [The discovery of the remains of a reptile (lacertide) in tuffs including within the Permian quartz porphyry of Trentino.]
Leonardi P 1959. Tridentinosaurus antiquus Gb. Dal Piaz, rettile protorosauro permiano del Trentino orientale. Memorie di Scienze Geologiche 21: 3–15.
Ronchi, A., Sacchi, E., Romano, M., and Nicosia, U. 2011. A huge caseid pelycosaur from north−western Sardinia and its bearing on European Permian stratigraphy and palaeobiogeography. Acta Palaeontologica Polonica 56 (4): 723–738.
Rossi V et al. 2021. New analyses of the “soft tissues” of the Italian tetrapod Tridentinosaurus antiquus. Insight on taphonomy and conservation history. EAVP abstract 2021.


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