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A diadectid skin impression and its implications for the evolutionary origin of epidermal scales

The Royal Society
Biology Letters
Authors:
Sebastian Voigt at Urweltmuseum GEOSKOP / Burg Lichtenberg (Pfalz)
Sebastian Voigt
  • Urweltmuseum GEOSKOP / Burg Lichtenberg (Pfalz)
Gabriela Calábková at Moravské zemské muzeum
Gabriela Calábková
Izabela Ploch at Państwowy Instytut Geologiczny
Izabela Ploch
Vojtěch Nosek at Masaryk University
Vojtěch Nosek
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Abstract and Figures

Corneous skin appendages are not only common and diverse in crown-group amniotes but also present in some modern amphibians. This raises the still unresolved question of whether the ability to form corneous skin appendages is an apomorphy of a common ancestor of amphibians and amniotes or evolved independently in both groups. So far, there is no palaeontological contribution to the issue owing to the lack of keratin soft tissue preservation in Palaeozoic anamniotes. New data are provided by a recently discovered ichnofossil specimen from the early Permian of Poland that shows monospecific tetrapod footprints associated with a partial scaly body impression. The traces can be unambiguously attributed to diadectids and are interpreted as the globally first evidence of horned scales in tetrapods close to the origin of amniotes. Taking hitherto little-noticed scaly skin impressions of lepospondyl stem amniotes from the early Permian of Germany into account, the possibility has to be considered that the evolutionary origin of epidermal scales deeply roots among anamniotes.
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A diadectid skin impression and its
implications for the evolutionary origin of
epidermal scales
Sebastian Voigt1, Gabriela Calábková2, Izabela Ploch3, Vojtěch Nosek4, Wojciech
Pawlak5, Paweł Raczyński6, Frederik Spindler7 and Ralf Werneburg8
1Urweltmuseum GEOSKOP, Burgstr. 19, Thallichtenberg 66871, Germany
2Department of Geology and Paleontology, Moravian Museum, Zelný Trh 6, Brno 659 37, Czech Republic
3Polish Geological Institute – National Research Institute, Rakowiecka 4, Warszawa 00-975, Poland
4Department of Archaeology and Museology, Faculty of Arts, Masaryk University, Joštova 220/13, Brno 662 43,
Czech Republic
5Department of Biology, University of Warsaw, Miecznikowa 1, Warszawa 02-089, Poland
6Institute of Geological Sciences, Wrocław University, Pl. Maksa Borna 9, Wrocław 50-204, Poland
7Sudetenstr. 16, Kipfenberg 85110, Germany
8Naturhistorisches Museum Schloss Bertholdsburg Schleusingen, Burgstr. 6, Schleusingen 98553, Germany
SV,0000-0003-4370-1731
Corneous skin appendages are not only common and diverse in crown-
group amniotes but also present in some modern amphibians. This raises
the still unresolved question of whether the ability to form corneous skin
appendages is an apomorphy of a common ancestor of amphibians and
amniotes or evolved independently in both groups. So far, there is no
palaeontological contribution to the issue owing to the lack of keratin soft
tissue preservation in Palaeozoic anamniotes. New data are provided by a
recently discovered ichnofossil specimen from the early Permian of Poland
that shows monospecific tetrapod footprints associated with a partial scaly
body impression. The traces can be unambiguously attributed to diadectids
and are interpreted as the globally first evidence of horned scales in
tetrapods close to the origin of amniotes. Taking hitherto little-noticed scaly
skin impressions of lepospondyl stem amniotes from the early Permian
of Germany into account, the possibility has to be considered that the
evolutionary origin of epidermal scales deeply roots among anamniotes.
1. Introduction
The ability to produce corneous epithelial structures such as scales, feath-
ers, hair, claws, nails, hooves, beaks and horns is considered a significant
adaptation of vertebrate life on land [1–3]. Among living tetrapods, almost all
amniotes but also some amphibians have corneous skin appendages [2,4–6].
Whether the ability to form corneous skin appendages was already present
in a common ancestor of amphibians and amniotes or evolved independently
in both groups is a matter of debate [5–9]. The fossil record has contributed
little to solve this question as there is no clear evidence for corneous epithelial
structures of stem amniotes yet. Corneous structures are composed of various
proteins (such as keratin and keratin-associated proteins) which as organic
compounds rarely preserve as fossils, especially in the Palaeozoic [2,10–12].
Here, we present a recently discovered slab of Permian tetrapod ichno-
fossils that is remarkable in three ways: (i) the slab shows footprints with
associated scaly skin impression that, judging by size and relative position,
originates from the producer of the footprints; (ii) the footprints belong to a
well-known Permian tetrapod ichnotaxon, which is referred to as diadectids,
i.e. stem amniotes [13] or most basal representatives of the crown group
© 2024 The Author(s). Published by the Royal Society. All rights reserved.
Research
Cite this article: Voigt S, Calábková G, Ploch I,
Nosek V, Pawlak W, Raczyński P, Spindler F,
Werneburg R. 2024 A diadectid skin impression
and its implications for the evolutionary origin of
epidermal scales. Biol. Lett. 20: 20240041.
https://doi.org/10.1098/rsbl.2024.0041
Received: 23 January 2024
Accepted: 22 March 2024
Subject Category:
Palaeontology
Subject Areas:
palaeontology, evolution, developmental biology
Keywords:
early tetrapods, skin appendages, scale pattern,
corneous structures, palaeozoic
Author for correspondence:
Sebastian Voigt
e-mails: s.voigt@pfalzmuseum.bv-pfalz.de;
csebastian.voigt@gmail.com
ResearchGate has not been able to resolve any citations for this publication.
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