Ichnological evidence for meiofaunal bilaterians from the terminal Ediacaran and earliest Cambrian of Brazil

Author(s):Show less -

Parry, Luke A. ^{[1, 2]} ; Boggiani, Paulo C. ^[3] ; Condon, Daniel J. ^[4] ; Garwood, Russell J. ^{[5, 6]} ; Leme, Juliana de M. ^[3] ; McIlroy, Duncan ^[7] ; Brasier, Martin D. ^[8] ; Trindade, Ricardo ^[9] ; Campanha, Ginaldo A. C. ^[3] ; Pacheco, Mirian L. A. F. ^[10] ; Diniz, Cleber Q. C. ^[3] ; Liu, Alexander G. ^[11]

Affiliation:Show less -

^[1] Royal Ontario Museum, Palaeobiol, 100 Queens Pk, Toronto, ON M5S 2C6 - Canada

^[2] Univ Toronto, Dept Ecol & Evolutionary Biol, 25 Willcocks St, Toronto, ON M5S 3B2 - Canada

^[3] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, BR-05508080 Sao Paulo - Brazil

^[4] British Geol Survey, Isotope Geosci Lab, NERC, Keyworth NG12 5GG, Notts - England

^[5] Univ Manchester, Sch Earth & Environm Sci, Manchester M13 9PL, Lancs - England

^[6] Nat Hist Museum, Dept Earth Sci, Cromwell Rd, London SW7 5BD - England

^[7] Mem Univ Newfoundland, Dept Earth Sci, Alexander Murray Bldg, 300 Prince Philip Dr, St John, NF A1B 3X5 - Canada

^[8] Univ Oxford, Dept Earth Sci, South Parks Rd, Oxford OX1 3AN - England

^[9] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Geofis, Rua Matao 1226, BR-05508900 Sao Paulo - Brazil

^[10] Univ Fed Sao Carlos, Dept Biol, Rodovia Joao Leme dos Santos, BR-18052780 Sorocaba - Brazil

^[11] Univ Cambridge, Dept Earth Sci, Downing St, Cambridge CB2 3EQ - England

• Document type: Journal article
• Source: NATURE ECOLOGY & EVOLUTION; v. 1, n. 10, p. 1455-1464, OCT 2017.
• Web of Science Citations: 22

Abstract

The evolutionary events during the Ediacaran-Cambrian transition (similar to 541 Myr ago) are unparalleled in Earth history. The fossil record suggests that most extant animal phyla appeared in a geologically brief interval, with the oldest unequivocal bilaterian body fossils found in the Early Cambrian. Molecular clocks and biomarkers provide independent estimates for the timing of animal origins, and both suggest a cryptic Neoproterozoic history for Metazoa that extends considerably beyond the Cambrian fossil record. We report an assemblage of ichnofossils from Ediacaran-Cambrian siltstones in Brazil, alongside U-Pb radioisotopic dates that constrain the age of the oldest specimens to 555-542 Myr. X-ray microtomography reveals three-dimensionally preserved traces ranging from 50 to 600 mu m in diameter, indicative of small-bodied, meiofaunal tracemakers. Burrow morphologies suggest they were created by a nematoid-like organism that used undulating locomotion to move through the sediment. This assemblage demonstrates animal-sediment interactions in the latest Ediacaran period, and provides the oldest known fossil evidence for meiofaunal bilaterians. Our discovery highlights meiofaunal ichnofossils as a hitherto unexplored window for tracking animal evolution in deep time, and reveals that both meiofaunal and macrofaunal bilaterians began to explore infaunal niches during the late Ediacaran. (AU)

• FAPESP's process: 09/02312-4 - Morphological reconstitution and systematic analysis of Corumbella werneri Hahn et al. 1982 (Tamengo Formation, Ediacaran, Corumbá Group), Mato Grosso do Sul, Brazil: paleoecological and taphonomical implications.
• Grantee: Mírian Liza Alves Forancelli Pacheco
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 10/02677-0 - Stable isotope records (C, O and Sr) of the Itapucumi Group and correlation with Corumbá Group (Ediacaran Period)
• Grantee: Paulo César Boggiani
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/17835-8 - Study of Raman Spectroscopy in fossildiagenesis and skeletogenesis: paleoecological and paleoevolutionary implications
• Grantee: Juliana de Moraes Leme Basso
• Support Opportunities: Regular Research Grants