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Cited by 18Paleontology and Evolutionary BiologyEvolution and Paleontology StudiesFossil Insects in Amber

Exceptional soft tissues preservation in a mummified frog-eating Eocene salamander

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Tissier, Jérémy, Rage, Jean-Claude, Laurin, Michel·2017·PeerJ
DOI 10.7717/peerj.3861PMC PMC5629955
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Abstract

Fossils are almost always represented by hard tissues but we present here the exceptional case of a three-dimensionally preserved specimen that was ‘mummified’ (likely between 40 and 34 million years ago) in a terrestrial karstic environment. This fossil is the incomplete body of a salamander, Phosphotriton sigei , whose skeleton and external morphology are well preserved, as revealed by phase-contrast synchrotron X-ray microtomography. In addition, internal structures composed of soft tissues preserved in three dimensions are now identified: a lung, the spinal cord, a lumbosacral plexus, the digestive tract, muscles and urogenital organs that may be cloacal glands. These are among the oldest known cases of three-dimensional preservation of these organs in vertebrates and shed light on the ecology of this salamander. Indeed, the digestive tract contains remains of a frog, which represents the only known case of an extinct salamander that fed on a frog, an extremely rare type of predation in extant salamanders. These new data improve our scarce knowledge on soft tissue anatomy of early urodeles and should prove useful for future biologists and palaeontologists working on urodele evolutionary biology. We also suggest that the presence of bat guano and carcasses represented a close source of phosphorus, favouring preservation of soft tissues. Bone microanatomy indicates that P. sigei was likely amphibious or terrestrial, and was probably not neotenic.

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  • Primitive lungs can be observed in several extant basal actinopterygians (bichirs, reedfish) and all extant sarcopterygians, as well as some fossils of coelacanths and salamanders.

    “In addition, primitive lungs, which originated from the respiratory pharynx and were located on the ventral side of the alimentary tracts, can be observed in several extant basal actinopterygians (bichirs, reedfish) and all extant sarcopterygians, as well as some fossils of coelacanths and salamanders (Cupello et al., 2017; Tissier et al., 2017) (Figure 1).”

    From Ancestral developmental potentials in early bony fish contributed to vertebrate water-to-land transition (2021) · cites this paper as Tissier et al., 2017

  • Homologous analyses suggest that some morphologies related to vertebrate land dispersal were already present in early bony fish species.

    “However, homologous analyses of these body forms and structures in more ancient species have suggested that some of the morphologies related to vertebrate land dispersal were already present in early bony fish species.”

    From Ancestral developmental potentials in early bony fish contributed to vertebrate water-to-land transition (2021) · cites this paper as Tissier et al., 2017

    The Discussion examines whether the Eocene salamander Phosphotriton sigei was amphibious or terrestrial. A separate Discussion passage mentions possible lungs in fossil fish, but does not connect them to land dispersal. Searches for homologous structures and early bony fish found no passage in our copy addressing the claimed evolutionary inference; page numbers were not provided. (LLM, conf=0.75)

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Research works printed but not linked: 2

  1. Francis ETB 1934 The anatomy of the salamander The Clarendon Press Oxford
  2. Schwermann AH Wuttke M Dos Santos Rolo T Caterino MS Bechly G Schmied H Baumbach T Van de Kamp T 2016b The fossil insects of the quercy region: a historical review Entomologie Heute 28 127 142

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Authors
Tissier, J., Rage, J.-C., & Laurin, M.
Affiliations
  • University of Fribourg (CH)
  • Centre National de la Recherche Scientifique (FR)
Corresponding author
Tissier, Jérémy
ORCID
Venue
PeerJ
Publisher
PeerJ
Published
2017-10-03
Volume
5
Pages
e3861
ISSN
2167-8359 (ISSN-L)
DOI
10.7717/peerj.3861
PMC
PMC5629955
OpenAlex
W2762754509
Cited by
18
References
29
Citations by year
2025: 1 · 2024: 2 · 2023: 3 · 2022: 3 · 2021: 2 · 2020: 1 · 2019: 1 · 2018: 5
FWCI
1.36
Type
journal article
Language
en
Open access
Licence
Locations
  • PeerJ (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • reroDoc Digital Library (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • CNRS the French Ministry of Research, and Sorbonne Universités
  • Swiss National Science Foundation (200021_162359)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Evolutionary Biology
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
  • Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Fossil Insects in Amber
Keywords
soft tissue preservation, lung, spinal cord, lumbosacral plexus, gastrointestinal tract, cloacal gland, frog predation, bat guano, phosphorus sources, bone microanatomy, neoteny

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