Tagasi otsingusse
Mark-Kurik, 1993b

Notes on the squamation in psammosteids

Mark-Kurik, E.
PDF
Aasta1993
Kirjastus.
AjakiriModern Geology
Köide18
Number1
Leheküljed107-114
Tüüpartikkel ajakirjas
Eesti autor
Keelinglise
Id699

Abstrakt

Of the numerous psammosteids' (Agnatha, Heterostraci) only one species, Drepanaspis gemuendenensis Schlüter (Lower Devonian, Rhineland), shows an articulated squamation and а we,U-preserved caudal fin. Drepanaspis exhibits the three main kinds of scales characteristic of all psammosteids: flank scales, ridge scales and tail fin scales. Narrow overlapping margins of scales are also а noteworthy feature in psammosteids. In this paper, partly preserved squamation of the Middle Devonian Schizosteus striatus ( Gross) and Psammosteus sp. is demonstrated. The Psammosteus species differ from other psammosteids in possessing small and rather uniform scales. This type of squamation could hardly have Ьееn derived from that of Psammolepis and, consequently, Psammosteus was not а descendant of Psammolepis.

Viimati muudetud: 6.3.2021
KIKNATARCSARVTÜ Loodusmuuseumi geokogudEesti Loodusmuuseumi geoloogia osakond
Leheküljel leiduvad materjalid on enamasti kasutamiseks CC BY-SA litsensi alusel, kui pole teisiti määratud.
Portaal on osaks teadustaristust ning infosüsteemist SARV, majutab TalTech.
Open Book ikooni autor Icons8.