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Ecological innovations in the Cambrian and the origins of the crown group phyla
- Source :
- Philosophical Transactions of the Royal Society B: Biological Sciences
- Publication Year :
- 2016
- Publisher :
- Uppsala universitet, Institutionen för geovetenskaper, 2016.
-
Abstract
- Simulation studies of the early origins of the modern phyla in the fossil record, and the rapid diversification that led to them, show that these are inevitable outcomes of rapid and long-lasting radiations. Recent advances in Cambrian stratigraphy have revealed a more precise picture of the early bilaterian radiation taking place during the earliest Terreneuvian Series, although several ambiguities remain. The early period is dominated by various tubes and a moderately diverse trace fossil record, with the classical ‘Tommotian’ small shelly biota beginning to appear some millions of years after the base of the Cambrian at ca 541 Ma. The body fossil record of the earliest period contains a few representatives of known groups, but most of the record is of uncertain affinity. Early trace fossils can be assigned to ecdysozoans, but deuterostome and even spiralian trace and body fossils are less clearly represented. One way of explaining the relative lack of clear spiralian fossils until about 536 Ma is to assign the various lowest Cambrian tubes to various stem-group lophotrochozoans, with the implication that the groundplan of the lophotrochozoans included a U-shaped gut and a sessile habit. The implication of this view would be that the vagrant lifestyle of annelids, nemerteans and molluscs would be independently derived from such a sessile ancestor, with potentially important implications for the homology of their sensory and nervous systems.
- Subjects :
- 0301 basic medicine
Central Nervous System
Lophotrochozoa
Biology
Trace fossil
General Biochemistry, Genetics and Molecular Biology
nervous systems
03 medical and health sciences
Paleontology
Naturvetenskap
Animals
Spiralia
Homology (anthropology)
Geosciences, Multidisciplinary
Ecosystem
Deuterostome
Ecology
Phylum
Fossils
Articles
Crown group
biology.organism_classification
Invertebrates
Multidisciplinär geovetenskap
crown group
030104 developmental biology
Period (geology)
gut
General Agricultural and Biological Sciences
Natural Sciences
Research Article
trace fossils
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Philosophical Transactions of the Royal Society B: Biological Sciences
- Accession number :
- edsair.doi.dedup.....6c31712a395a6aa95f0260e95201fe7b