Cephalic Segmentation and Sutures in Trilobites
نویسندگان
چکیده
منابع مشابه
Trilobites
Avery’s purification of transforming principle and Kornberg’s purification of the first DNA polymerase, the experiments I have described were of a new type where what might be called the chemical behaviour of genetic material was being analysed without the benefit of purification. And this has become the new style in biology, inaugurated in the late 1950s by Taylor, Meselson and Stahl. It was, ...
متن کاملThe stability of thoracic segmentation in trilobites: a case study in developmental and ecological constraints.
The decline in origination rate of new metazoan body plans following the Cambrian radiation has been suggested to reflect developmental canalization in derived taxa, limiting their ability to evolve forms with radically different morphotypes. Segmentation is a fundamental aspect of arthropod body plan, and here we show that a derived trilobite that secondarily converged on a morphotype characte...
متن کاملAncestral Patterning of Tergite Formation in a Centipede Suggests Derived Mode of Trunk Segmentation in Trilobites
Trilobites have a rich and abundant fossil record, but little is known about the intrinsic mechanisms that orchestrate their body organization. To date, there is disagreement regarding the correspondence, or lack thereof, of the segmental units that constitute the trilobite trunk and their associated exoskeletal elements. The phylogenetic position of trilobites within total-group Euarthropoda, ...
متن کاملDevelopmental trait evolution in trilobites.
We performed a tree-based analysis of trilobite postembryonic development in a sample of 60 species for which quantitative data on segmentation and growth increments between putative successive instars are available, and that spans much of the temporal, phylogenetic, and habitat range of the group. Three developmental traits were investigated: the developmental mode of trunk segmentation, the a...
متن کاملPhylogenetic and Biogeographic Analysis of Sphaerexochine Trilobites
BACKGROUND Sphaerexochinae is a speciose and widely distributed group of cheirurid trilobites. Their temporal range extends from the earliest Ordovician through the Silurian, and they survived the end Ordovician mass extinction event (the second largest mass extinction in Earth history). Prior to this study, the individual evolutionary relationships within the group had yet to be determined uti...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Geological Magazine
سال: 1950
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800077153