O surgimento dos bilatérios na fauna de Ediacara: congruência entre os registros genéticos e geológico dos fósseis

The Ediacaran emergence of bilaterians: congruence between the genetic and the geological fossil records

1. Kevin J Peterson1*, 
2. James A Cotton2, 
3. James G Gehling3,4,5 and
4. Davide Pisani6*

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Author Affiliations

1. ¹Department of Biological Sciences, Dartmouth College 

   Hanover, NH 03755, USA
2. ²School of Biological and Chemical Sciences, Queen Mary, University of London 

   Mile End Road, London E1 4NS, UK
3. ³South Australian Museum 

   North Terrace, Adelaide, South Australia 5000, Australia
4. ⁴Department of Geological Sciences, Queen's University 

   Kingston, Ontario, Canada K7L 3N6
5. ⁵Department of Earth Sciences, Monash University 

   Clayton, Victoria 3168, Australia
6. ⁶Laboratory of Evolutionary Biology, The National University of Ireland

   Maynooth, County Kildare, Ireland

1. Authors for correspondence (kevin.j.peterson@dartmouth.edu) (davide.pisani@nuim.ie)

Abstract

Unravelling the timing of the metazoan radiation is crucial for elucidating the macroevolutionary processes associated with the Cambrian explosion. Because estimates of metazoan divergence times derived from molecular clocks range from quite shallow (Ediacaran) to very deep (Mesoproterozoic), it has been difficult to ascertain whether there is concordance or quite dramatic discordance between the genetic and geological fossil records. Here, we show using a range of molecular clock methods that the major pulse of metazoan divergence times was during the Ediacaran, which is consistent with a synoptic reading of the Ediacaran macrobiota. These estimates are robust to changes in priors, and are returned with or without the inclusion of a palaeontologically derived maximal calibration point. Therefore, the two historical records of life both suggest that although the cradle of Metazoa lies in the Cryogenian, and despite the explosion of ecology that occurs in the Cambrian, it is the emergence of bilaterian taxa in the Ediacaran that sets the tempo and mode of macroevolution for the remainder of geological time.

Keywords:

• molecular clock
 
• Cambrian explosion
 
• fossil calibration
 
• Ediacaran

Footnotes

• One contribution of 17 to a Discussion Meeting Issue ‘Evolution of the animals: a Linnean tercentenary celebration’.
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