The presence of osteostracan, anaspid, thelodont, acanthodian and possible placoderm
remains in the Eastport Formation of Maine mirrors the vertebrate fauna known elsewhere in the Lower Old Red Sandstone of eastern North America and Europe (e.g., Denison 1956; the 'Cephaslaspid province of Young 1981; the North Atlantic province of Dineley and Loeffler 1993; and the 'central Appalachian zone' of Blieck and Janvier 1999, Burrow et al.
Like Entelognathus, Qilinyu had a three-part jaw, though the creature looked a bit more like a typical placoderm
, Ahlberg says.
It was assumed placoderms
died out and a different group evolved into bony fish.
2003), disarticulated cephalaspids, placoderms
and acanthodians, and both articulated and disarticulated eurypterids (Miller 2007a).
It is a member of an extinct group of fish called placoderms
whose heads and bodies were mostly covered in armor, with jaws that had bony plates, called gnathal plates, which acted like teeth.
, these extinct animals were among the earliest vertebrates with jaws.
The unusual appearance of this miniscule 390-millionyear-old fossil had us wondering at first if it might indeed be part of a placoderm
, a peculiar group of armoured fishes known only from fossils ...
The Late Devonian placoderm
Aspidichthys Newberry, 1873 from the Holy Cross Mountains, Poland.
The Andreyevka-2 community including antiarch placoderms
, acanthodians, chondrichthyans and osteichthyans, as well as tetrapods, has been discussed on repeated occasions by the first author of this paper (Lebedev 1986, 1992, 2013; Lebedev et al.
Actinolepis tuberculata Agassiz, Homostius sp., Byssacanthus dilatatus (Eichwald); acanthodians Archae-acanthus quadrisulcatus Kade, Diplacanthus kleesmentae Valiukevicius, Acanthodes?
They are represented by undetermined placoderms
, acanthodians and sarcopterygians (Fig.
However, a closer inspection by Long and research team revealed they were the tiny bones of unborn fish from two adult species of arthrodires (Incisoscutum ritchiei) - the biggest and most diverse placoderm