Early Devonian fishes from coastal De Long Strait, central Chukotka, Arctic Russia Author Mark-Kurik, Elga Author Blieck, Alain Author Burrow, Carole J. Author Turner, Susan text Geodiversitas 2013 2013-09-27 35 3 545 578 http://dx.doi.org/10.5252/g2013n3a3 journal article 10.5252/g2013n3a3 1638-9395 5372262 HETEROSTRACI ? indet. ( Fig. 6I ) MATERIAL. — Specimen GIT 580-8: isolated tessera or platelet. LOCALITY AND STRATIGRAPHIC HORIZON. — Same as specimens GIT n°580-1, 2, 3, 4, 6 and 7: locality (sample) 73, Tonnel’nyj Brook, south of De Long Strait, Chukotka ; Lower Member (1) of Enmakaj Formation, Lochkovian. DESCRIPTION ħis specimen is an isolated square-shaped element (either a tessera or platelet), partially broken, and with an altered surface. It bears a single, probably central, star-shaped tubercle ( Fig. 6I ). Because it is larger ( c. 3.2 mm long for its preserved part) than all other tesserae that have been prepared from sample 73 of the Coast section, we suggest that it might correspond to a different taxon. Furthermore, with such a small sample (a single specimen), no thin section has been made, and thus its histology is not confirmed as being of a heterostracan.