Chelichnus cf. duncani ( Owen, 1842 )

Ptaszyński, Tadeusz & Niedźwiedzki, Grzegorz, 2004, Late Permian vertebrate tracks from the Tumlin Sandstone, Holy Cross Mountains, Poland, Acta Palaeontologica Polonica 49 (2), pp. 289-320 : 315-316

publication ID	https://doi.org/ 10.5281/zenodo.13510407
persistent identifier	https://treatment.plazi.org/id/03F387F5-162B-7C24-FFBE-FA1E8E766362
treatment provided by	Felipe
scientific name	Chelichnus cf. duncani ( Owen, 1842 )
status

Treatment

Chelichnus cf. duncani ( Owen, 1842)

Figs. 30B, C View Fig , 31A–C View Fig , 33A–C View Fig .

“Protorosuchia indet.” Ptaszyński 2000b: fig. 5, specimen described in this paper as Muz. PIG OS−220/68: 1, 2 ( Fig. 30B View Fig ).

Material.—Muz. PIG OS−220/39: 20–27 the best visible part of the trackway from the slab Muz. PIG OS−220/39 ( Figs. 31A View Fig , 33A View Fig ); Muz. PIG OS−220/62: 1, 2 set of left pedal and manual (poorly preserved) imprints ( Figs. 31C View Fig , 33C View Fig ); Muz. PIG OS−220/68: 1, 2 set of poorly and shallowly impressed left pedal and manual imprints ( Fig. 30B View Fig ).

Description.—Trackway Muz. PIG OS−220/39: 20–27 ( Figs. 31A View Fig , 33A View Fig ) is the most completely preserved part of the larger association of poorly preserved imprints. Manual and pedal imprints are not distinguishable. Imprints are about five centimetres in diameter. Their axes are approximately parallel to the trackway. The width of pace can be determined at about 7 cm; pace angulation attains about 90°. The best preserved footprint, specimen Muz. PIG OS−220/39: 23 is 47 mm wide and 39 mm long. Digits I–IV diverge of 30°, while the divarication of digits I–V attains 75°. At least first four digits end sharply and possibly had claw marks.

Digits I and II are 20 and 23 mm long. Digits III and IV are equal in length, attaining 25 mm. Digit V is somewhat shorter, 23 mm. The separation of pedal digit II and IV bases is 13 mm. In the set of left imprints Muz. PIG OS−220/62: 1, 2 both imprints are wide and relatively short. The second one, interpreted as manual imprint is poorly visible. The first one, Muz. PIG OS−220/62: 1 ( Figs. 31C View Fig , 33C View Fig ) has five digits. Possibly all digits have claw marks, distinctly visible on tips of II, III, IV and V. The width of the footprint is 85 mm, while its length attains about 75 mm. The length of digits, which may be slightly deformed by the sliding movement, increase from I to IV: 20, 40, 50, 50 mm (the III and IV are equal in length). The length of digit V attains approximately 40 mm. Digits I–V, I–IV, II–IV diverge of relatively low angles: 55, 25, and 15°, respectively. The separation of pedal digit II and IV bases is 35 mm.

Specimen Muz. PIG OS−220/68: 1, 2 ( Fig. 30B View Fig ) shows set of left pedal and manual imprints. The shape of footprints, except for pedal digits II–IV, is not clearly visible. Pedal imprint is about 80 mm long and 75 mm wide. Digits I–V diverge of 75°. The separation of pedal digit II and IV bases is 30 mm. In the specimen Muz. PIG OS−220/68: 2 interpreted as somewhat smaller, manual imprint, the distance between externally situated digits, possibly I–IV attains 50 mm; their divarication attains 84°. Indeterminable, rounded, imprints with a diameter of 50–80 mm imprints, with no visible details of the foot, occurring on upper sides of layers, sometimes with sand crescents around (Muz. PIG OS−220/65, Muz. PIG OS−220/66, Muz. PIG OS−220/67). Although not determinable, they possibly represent Chelichnus .

Remarks.—Because no clear trackway known, and presence of specimens mainly as isolated, poorly preserved imprints, their exact determination is difficult. According to the newest revision ( McKeever and Haubold 1996) they may be regarded as relatively small (Muz. PIG OS−220/39: 20–27) and relatively large (Muz. PIG OS−220/62: 1) representatives of Chelichnus cf. duncani ( Owen, 1842) . Among footprints from Tumlin Gród, there are observed atypically and not completely impressed, deformed by the sliding movement, attributed to Rhynchosauroides kuletae ichnosp. nov. ( Fig. 35A View Fig 4 View Fig ),? Phalangichnus gradzinskii ichnosp. nov. ( Fig. 34A, B View Fig ) and Palmichnus lacertoides ichnosp. nov. ( Fig. 35C View Fig ), which if found as isolated imprints, could be erroneously determined as Chelichnus representatives.

We believe, that vertebrate ichnotaxa should be uniform class of objects. It means, that all should be described as objects with comparable and compared features. Only under this condition vertebrate tracks can be treated as fully valuable systematic (parataxonomic) group. It should be accepted, that considerable part of specimens can not be exactly determined rather, than create a different parataxonomical category of poorly preserved tracks originated in the Late Permian dune environment (see McKeever and Haubold 1996). Erecting not fully comparable categories of ichnotaxonomic objects, with diagnostic criteria not uniform, but depending on facies, age and kind of taxon, is not a recommendable practice, making different ichnofaunas incomparatible (not described with uniform criteria). The data derived from Tumlin Sandstone show that it may lead to erroneous conclusions concerning poor diversity of the Late Permian vertebrate ichnofaunas (see McKeever and Haubold 1996).

The problem of Anhomoiichnium and tracks not exactly determined. The problem of unsatisfactory preservation is connected with the formal existence of the questionable (see Haubold et al. 1995; Haubold 1996; Haubold and Stapf 1998) ichnogenus Anhomoiichnium Dozy, 1935 with the ichnospecies A. diversum ( Schmidt, 1959) . We found no trackways or isolated imprints unequivocally attributable to this ichnospecies. Some poorly preserved or deformed specimens representing possibly Paradoxichnium tumlinense ichnosp. nov. (Muz. PIG OS−220/47: 1 isolated pedal imprint; not numbered set of right imprints on the slab Muz. PIG OS−220/27, Fig. 35A View Fig 1 View Fig ) and some imprints of Palmichnus lacertoides ichnosp. nov. ( Fig. 35C View Fig ) exhibit shape and characteristic deformations very similar to those of Anhomoiichnium (see Fichter 1983b: figs. 27–29). At present, the existence of Anhomoiichnium representatives in Tumlin Sandstone cannot be confirmed.

During field investigations we found many trackways and isolated imprints not preserved well enough for detailed determination. Some of them show only digit tips imprints situated characteristic as in Phalangichnus trackways ( Fig. 34A, B View Fig ). Others show mostly manual imprints visible ( Fig. 35A View Fig 1 View Fig , A 3 View Fig ). Many tracks are too poorly preserved to account them to any ichnogenus or ichnospecies ( Fig. 32C, D View Fig ), but their presence supplements the knowledge concerning this ichnocoenose and is of big meaning to the whole concept of the assemblage. Systematic position of those problematic specimens may be explained in future but their presence can be here already pointed out.