Journal article
Evolution of Bony Fish: Without a Cryptic Sarcopterygian, It May Have Evolved Actinopterygians into Terrestrial Animals
Diversity (Basel), Vol.18(5), 293
05/14/2026
DOI: 10.3390/d18050293
Abstract
The evolution of Osteichthyes began with a split into two major lineages: Sarcopterygii (lobe-finned fishes) and Actinopterygii (ray-finned fishes). In one lineage—sarcopterygians—some groups evolved robust internal bones and limb-like fins and ultimately gave rise to semi- and fully terrestrial tetrapods; the other lineage—actinopterygians—remained primarily aquatic and later radiated into the diverse teleosts. Repeated mass extinction events and ongoing genetic divergence allowed novel functions and new niches to be exploited, a pattern especially evident in recent analyses of teleost diversification. Lobe-finned fishes characteristically possess an endoskeleton fin architecture, whereas ray-finned fishes bear dermal fin rays built on a different structural plan. Primitive Osteichthyes also show an early origin of paired air-spaces (lungs), but many derived actinopterygians modified this ancestral condition into a dorsal swim bladder. Imagining a world without sarcopterygians or tetrapods highlights how teleosts might have convergently colonized many terrestrial-associated niches; although significant developmental and structural hurdles would have made such a transition challenging, this thought experiment underscores the cascading ecological consequences that the loss of a major clade can produce. Ecosystems thrive on diversity and adaptability, and episodes of environmental upheaval—such as the Silurian and Devonian extinctions—often catalyze rapid evolutionary change.
Details
- Title: Subtitle
- Evolution of Bony Fish: Without a Cryptic Sarcopterygian, It May Have Evolved Actinopterygians into Terrestrial Animals
- Creators
- Bernd Fritzsch - University of Nebraska Medical CenterEbenezer N. Yamoah - University of Arizona
- Resource Type
- Journal article
- Publication Details
- Diversity (Basel), Vol.18(5), 293
- DOI
- 10.3390/d18050293
- ISSN
- 1424-2818
- eISSN
- 1424-2818
- Publisher
- MDPI
- Grant note
- National Institutes of Health: DC022866, DC016099, AG051443
E.N.Y. and B.F. were partly supported by National Institutes of Health grants DC022866, DC016099, and AG051443. No AI was used for writing/grammar and figures.
- Language
- English
- Date published
- 05/14/2026
- Academic Unit
- Biology; Craniofacial Anomalies Research Center
- Record Identifier
- 9985164731302771
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