Pelvic claspers confirm chondrichthyan-like internal fertilization in arthrodires

• Recent finds(1,2) demonstrate that internal fertilization and   viviparity (live birth) were more widespread in the Placodermi, an   extinct group of armoured fishes, than was previously realized.   Placoderms represent the sister group of the crown group jawed   vertebrates (Gnathostomata)(3,4), making their mode(s) of reproduction   potentially informative about primitive gnathostome conditions. An   ossified pelvic fin basipterygium discovered in the arthrodire   Incisoscutum ritchiei was hypothesized to be identical in males and   females, with males presumed to have an additional cartilaginous   element or series forming a clasper. Here we report the discovery of a   completely ossified pelvic clasper in Incisoscutum ritchiei (WAM   03.3.28) which shows that this interpretation was incorrect: the   basipterygium described previously(1) is in fact unique to females. The   male clasper is a slender rod attached to a square basal plate that   articulates directly with the pelvis. It carries a small cap of dermal   bone covered in denticles and small hooks that may be homologous with   the much larger dermal component of the ptyctodont clasper.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

palaeontology

evolution

fossil

vertebrate

reproduction

Devonian

placoderm

clasper

Biology

Biologi

Biologi med inriktning mot evolutionär organismbiologi

Biology with specialization in Evolutionary Organismal Biology

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)