A French Jurassic plant which Saporta[1475] made the type of a new genus Scleropteris, and described as S. Pomelii, appears to be indistinguishable from Dichopteris.
Dichopteris, though conveniently retained as a distinct genus, agrees so closely, in the broad and forked rachis and in the fleshy pinnules, with Thinnfeldia that it would seem reasonable to regard the two genera as members of the same group.
Several authors have drawn attention to the striking resemblance in form and venation between the fronds of the Palaeozoic genus Odontopteris and those of Ctenopteris and Thinnfeldia. In Odontopteris, as in Neuropteris, another Palaeozoic genus, the rachis occasionally bifurcates as in Thinnfeldia and Dichopteris, and the ultimate segments of some species of Odontopteris ([fig. 366], A) are practically identical with those of Thinnfeldia and Ptilozamites.
Odontopteris is probably a Pteridosperm. There is no adequate reason for supposing that this group of plants which played a prominent part in the Permo-Carboniferous floras was no longer in existence during the Mesozoic era.
Odontopteris.
Brongniart[1476] instituted the genus Odontopteris for compound fronds from the Coal-Measures characterised by pinnules attached by the whole breadth of the base and traversed by numerous forked veins. Odontopteris is very rare in British Carboniferous rocks and “appears to be restricted to the Middle and Upper Coal-Measures[1477].”
Fig. 364.
- Alethopteris lonchitica (Schloth.). ½ nat. size.
- Mariopteris muricata (Schloth.). × 2.
- Odontopteris cf. alpina (Presl). ⅗ nat. size.
- O. cf. alpina. Portion of pinna enlarged.
(A–D. From photographs by Dr Kidston.)]