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Article: New information on the Jurassic lepidosauromorph Marmoretta oxoniensis

Papers in Palaeontology - Volume 7 Issue 1 - Cover
Publication: Papers in Palaeontology
Volume: 7
Part: 4
Publication Date: November 2021
Page(s): 2255 2278
Author(s): Elizabeth F. Griffiths, David P. Ford, Roger B.J. Benson, and Susan E. Evans
DOI: 10.1002/spp2.1400
Addition Information

How to Cite

GRIFFITHS, E.F., FORD, D.P., BENSON, R.B., EVANS, S.E. 2021. . Papers in Palaeontology, 7, 4, 2255-2278. DOI: /doi/10.1002/spp2.1400

Author Information

  • Elizabeth F. Griffiths - Department of Earth Sciences University of Oxford South Parks Road Oxford OX1 3AN UK
  • David P. Ford - Department of Earth Sciences University of Oxford South Parks Road Oxford OX1 3AN UK
  • David P. Ford - Evolutionary Studies Institute University of the Witwatersrand Johannesburg South Africa
  • Roger B.J. Benson - Department of Earth Sciences University of Oxford South Parks Road Oxford OX1 3AN UK
  • Susan E. Evans - Research Department of Cell and Developmental Biology University College London London WC1E 6BT UK

Publication History

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    Abstract

    The earliest known crown-group lepidosaurs are known from the Middle Triassic; however, their stem group is poorly sampled, with only a few representative fossils found. This is partly due to the small size and delicate bones of early stem-lepidosaurs (= non-lepidosaurian lepidosauromorphs), which make both preservation in the fossil record and subsequent discovery less likely. The Middle Jurassic lepidosauromorph Marmoretta oxoniensis is re-examined using high-resolution micro-computed tomography to reveal parts of the skull anatomy that were previously unknown. These include a squamosal, postorbital, more complete parietal, pterygoids, and an articulated posterior section of the mandible. Some differences between this and other Marmoretta specimens were identified as a result, such as the arrangement of palatal teeth and the shape of the parabasisphenoid. The status of Marmoretta as a stem-lepidosaur or stem-squamate has been debated. To evaluate this, we tested the phylogenetic position of Marmoretta by including our new data in an adapted phylogenetic character matrix. We recover Marmoretta as a stem-lepidosaur and sister to Fraxinisaura rozynekae. Our findings support the hypothesis that both taxa belonged to a clade of non-lepidosaurian lepidosauromorphs that co-existed with lepidosaurs into the Middle Jurassic.

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