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Cited by 123Evolution and Paleontology StudiesPaleontology and Evolutionary BiologyPlant Diversity and Evolution

The oldest platypus and its bearing on divergence timing of the platypus and echidna clades

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Rowe, Timothy, Rich, Thomas H., Vickers-Rich, Patricia, Springer, Mark, Woodburne, Michael O.·2008·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.0706385105PMC PMC2234122
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Abstract

Monotremes have left a poor fossil record, and paleontology has been virtually mute during two decades of discussion about molecular clock estimates of the timing of divergence between the platypus and echidna clades. We describe evidence from high-resolution x-ray computed tomography indicating that Teinolophos , an Early Cretaceous fossil from Australia's Flat Rocks locality (121–112.5 Ma), lies within the crown clade Monotremata, as a basal platypus. Strict molecular clock estimates of the divergence between platypus and echidnas range from 17 to 80 Ma, but Teinolophos suggests that the two monotreme clades were already distinct in the Early Cretaceous, and that their divergence may predate even the oldest strict molecular estimates by at least 50%. We generated relaxed molecular clock models using three different data sets, but only one yielded a date overlapping with the age of Teinolophos . Morphology suggests that Teinolophos is a platypus in both phylogenetic and ecological aspects, and tends to contradict the popular view of rapid Cenozoic monotreme diversification. Whereas the monotreme fossil record is still sparse and open to interpretation, the new data are consistent with much slower ecological, morphological, and taxonomic diversification rates for monotremes than in their sister taxon, the therian mammals. This alternative view of a deep geological history for monotremes suggests that rate heterogeneities may have affected mammalian evolution in such a way as to defeat strict molecular clock models and to challenge even relaxed molecular clock models when applied to mammalian history at a deep temporal scale.

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  • This divergence estimate is similar to previous estimates but seems at odds with fossil evidence, perhaps owing to relatively recent reductions of mutational rates in the monotreme lineage.

    “Although similar to previous estimates 32 , this value seems to be at odds with fossil evidence, perhaps owing to relatively recent reductions of mutational rates in the monotreme lineage 33 .”

    From Genome analysis of the platypus reveals unique signatures of evolution (2008) · cites this paper as [33]

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Authors
Rowe, T., Rich, T. H., Vickers-Rich, P., Springer, M., & Woodburne, M. O.
Affiliations
  • The University of Texas at Austin (US)
  • Museums Victoria (AU)
  • Monash University (AU)
  • University of California, Riverside (US)
  • Museum Of Northern Arizona (US)
ORCID
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2008-01-29
Volume
105
Issue
4
Pages
1238-1242
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.0706385105
PMC
PMC2234122
OpenAlex
W2103506571
Cited by
123
References
66
Citations by year
2026: 2 · 2025: 2 · 2024: 1 · 2023: 3 · 2022: 3 · 2021: 4 · 2020: 9 · 2019: 6 · 2018: 4 · 2017: 7 · 2016: 16 · 2015: 4 · 2014: 9 · 2013: 10 · 2012: 10
FWCI
8.37
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Science Foundation (0208675, 0531767)
  • University of Texas at Austin
Topics
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Evolutionary Biology
  • Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Plant Diversity and Evolution
Keywords
platypus, echidna, monotremes, molecular clock, relaxed molecular clock, Lower Cretaceous, rate heterogeneity, computed tomography
MeSH terms
Animals, Australia, Tachyglossidae, Fossils, Phylogeny, Platypus, Time, Tomography, X-Ray Computed, Evolution, Molecular

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