INVESTIGADORES
VACCARI Norberto Emilio
artículos
Título:
Cambrian origins and affinities of an enigmatic fossil group of arthropods
Autor/es:
VACCARI N. E, G.E. EDGECOMBE Y C. ESCUDERO,
Revista:
NATURE
Editorial:
Nature Publishing Group
Referencias:
Lugar: Londres; Año: 2004 vol. 430 p. 554 - 557
ISSN:
0028-0836
Resumen:
Euthycarcinoids are one of the most enigmatic arthropod groups,
having been assigned to nearly all major clades of Arthropoda.
Recent work has endorsed closest relationships with crustaceans
or a myriapodhexapod assemblage, a basal position in the
Euarthropoda, or a placement in the Hexapoda or hexapod
stem group. Euthycarcinoids are known from 13 species ranging
in age from Late Ordovician or Early Silurian to Middle Triassic,
all in freshwater or brackish water environments6. Here we
describe a euthycarcinoid from marine strata in Argentina dating
from the latest Cambrian period, extending the groups record
back as much as 50 million years. Despite its antiquity and
marine occurrence, the Cambrian species demonstrates that
morphological details were conserved in the transition to fresh
water. Trackways in the same unit as the euthycarcinoid
strengthen arguments that similar traces of subaerial origin
from Cambro-Ordovician rocks were made by euthycarcinoids.
Large mandibles in euthycarcinoids are confirmed by the
Cambrian species. A morphology-based phylogeny resolves
euthycarcinoids as stem-group Mandibulata, sister to the Myriapoda
and Crustacea plus Hexapoda.