(London, Richard Taylor and William Francis, 1858). 4to. No wrappers as extracted from "Philosophical Transactions", Vol. 148 - Part I, Pp. 169-184 a. 3 lithographed plates. 2 plates with some brownspots.
First printing of this paper which describes a new group of extinct reptiles.
"Placodonts were peculiar, mollusc-eating marine reptiles known only from the Triassic of Europe and the Middle East. Looking something like a cross between a walrus and a turtle, they came in armoured and unarmoured varieties (see below) and were first discovered by Georg Münster in 1830. Seeking help from the great ichthyologist Louis Agassiz, Münster misidentified these teeth as those of pycnodont fishes, and gave them the name Placodus. Richard Owen realised that Placodus represented a new group of reptiles, which he officially recognised in 1858 (Owen 1858). Variously allied over the years with synapsids, ichthyosaurs and araeoscelidans, placodonts have proved to be strongly modified members of the Sauropterygia, the position that was originally advocated for them when Owen created this group in 1860."(Darren Naish in "Placodonts", 2000).