4.8 Article

Morphometric analysis of lungfish endocasts elucidates early dipnoan palaeoneurological evolution

Journal

ELIFE
Volume 11, Issue -, Pages -

Publisher

eLIFE SCIENCES PUBL LTD
DOI: 10.7554/eLife.73461

Keywords

dipnoi; endocast; tomography; palaeoneurology; palaeozoic; PCA; Other

Categories

Funding

  1. Australian Research Council [DP160102460, DP200103398]
  2. Flinders University
  3. Knut och Alice Wallenbergs Stiftelse
  4. Natural Sciences and Engineering Research Council of Canada
  5. Callidus Services Ltd UK
  6. Australian Research Council [DP200103398] Funding Source: Australian Research Council

Ask authors/readers for more resources

This study utilized X-ray tomography to examine the endocasts of ancient lungfish, revealing that the olfactory region is more plastic and undergoes significant changes in most taxa. Additionally, the semicircular canals form an integrated module, while the utriculus and sacculus vary independently.
The lobe-finned fish, lungfish (Dipnoi, Sarcoptergii), have persisted for ~400 million years from the Devonian Period to present day. The evolution of their dermal skull and dentition is relatively well understood, but this is not the case for the central nervous system. While the brain has poor preservation potential and is not currently known in any fossil lungfish, substantial indirect information about it and associated structures (e.g. labyrinths) can be obtained from the cranial endocast. However, before the recent development of X-ray tomography as a palaeontological tool, these endocasts could not be studied non-destructively, and few detailed studies were undertaken. Here, we describe and illustrate the endocasts of six Palaeozoic lungfish from tomographic scans. We combine these with six previously described digital lungfish endocasts (4 fossil and 2 recent taxa) into a 12-taxon dataset for multivariate morphometric analysis using 17 variables. We find that the olfactory region is more highly plastic than the hindbrain, and undergoes significant elongation in several taxa. Further, while the semicircular canals covary as an integrated module, the utriculus and sacculus vary independently of each other. Functional interpretation suggests that olfaction has remained a dominant sense throughout lungfish evolution, and changes in the labyrinth may potentially reflect a change from nektonic to near-shore environmental niches. Phylogenetic implications show that endocranial form fails to support monophyly of the 'chirodipterids'. Those with elongated crania similarly fail to form a distinct clade, suggesting these two paraphyletic groups have converged towards either head elongation or truncation driven by non-phylogenetic constraints.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.8
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available