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Character acquisition through geological time

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  • 1. Character Acquisition Through Geological Time Graeme T. Lloyd
  • 2. Tempo through timeDarwin Simpson Westoll 1859 1944 1949
  • 3. Lungfish tempo Westoll “A balanced rate summing up total morphologicalchange…would be of the greatest value for the study of 1949 evolution” - Simpson 1953
  • 4. Questions• Was Westoll right about lungfish evolution?• Do other ‘living fossils’ show the same pattern?• Do other taxa show a different pattern?• Are these results methodological artefacts or peculiarities of the fossil record?
  • 5. Problems with Westoll’s method• Only well known taxa can be included (Knoll et al. 1984)• Error bars required (constrain interpretation)• Ancestor artificial (Schopf 1984)• Reversals ignored (Derstler 1982)• Assumes stratigraphically ordered ancestor-descendant sequence
  • 6. Lungfish again (Lloyd in prep.)
  • 7. Actinistians Latimera chalumnae (Cloutier 1991)
  • 8. Sphenodontids (Lloyd in prep.) Paleoloricates (Cherns 2004) Sphenodon punctatus Neopilina galatheae Linguloids Xiphosurans (Cusack et al. 1999) (Moore et al. in prep.) Lingula Limulus polyphemus anatina
  • 9. Hipparionines (Alroy 1995)
  • 10. Temnopleurids Asteropygines (Jeffrey and Emlet 2003) (Lieberman and Kloc 1997) Artiodactyls Reptiles (Gentry and Hooker 1988) (Rieppel and deBraga 1996)
  • 11. Crocodilians (Gatesy et al. 2004) Alligator mississippiensis Gavialis lewisi Crocodylus niloticus
  • 12. Echinoids(Littlewood and Smith 1995) Tripneustes Spatangus Heliocidaris
  • 13. Common pattern =Common explanation
  • 14. Character distribution r2 = 0.98853131
  • 15. Character distributionSource Taxon R-squared PearsonAlroy 1995 Hipparionines 0.99 0.99Cherns 2004 Paleoloricates 0.98 0.99Cloutier 1991 Actinstians 0.99 0.99Cusack et al. 1999 Linguloids 0.97 0.99Gatesy et al. 2004 Crocodilians 0.87 0.93Gentry and Hooker 1988 Artiodactyls 0.75 0.75Jeffrey and Emlet 2003 Temnopleurids 0.78 0.89Lieberman and Kloc 1997 Asteropygines 0.96 0.98Littlewood and Smith 1995 Echinoids 0.81 0.90Lloyd in prep. Lungfish 0.99 0.99Lloyd in prep. Sphenodontids 0.96 0.98Moore et al. in prep. Xiphosurans 0.94 0.97Rieppel and deBraga 1996 Reptiles 0.95 0.97
  • 16. Taxon sampling vs. stratigraphic fit (Division of total timespan of clade into five equal bins) older younger
  • 17. Questions• Was Westoll right about lungfish evolution?• Do other ‘living fossils’ show the same pattern?• Do other taxa show a different pattern?• Are these results methodological artefacts or peculiarities of the fossil record?
  • 18. AcknowledgementsThis project was initially conceived by my supervisors, Mike Benton andPhil Donoghue. Rachel Moore, Matt Friedman and Hans-Peter Schultzekindly provided me with copies of their unpublished matrices. Members ofBristol’s Palaeontology Discussion Group provided useful comments andadvice on an earlier version of this presentation. This work represents partof my Ph.D. which is supported by NERC studentshipNER/S/A/2004/12222.
  • 19. FREE Postgraduate ConferenceDept. of Earth Sciences, University of Bristol 13th-14th April 2007Details and online registration at: <www.palass.org> Photo © S. Jasinoski