ProgPal 2025 abstracts: Tumelty on ray-finned fish radiation

Revisiting the Carboniferous radiation of ray-finned fish
Molly Tumelty – University of Birmingham wrote:

“Ray-finned fish, or actinopterygians, first evolved in the Devonian and subsequently  underwent significant diversification in the Carboniferous period.”

By contrast, fish with ray-fins had several origins in the large reptile tree (LRT, 2338 taxa). Evidently professors and their textbooks are teaching out-dated information at the University of Birmingham.

“Today, they make up 50% of vertebrate species. The earliest diverging group of actinopterygians are called polypterids, but their fossil record only stems back to the Triassic, despite molecular clock divergence estimates predicting a late Devonian early Carboniferous origin.”

First: paleontologists need to avoid ‘molecular clocks’ based on genes. Too often genes produce false positives and genes cannot be used with Devonian and Carboniferous taxa.

Second: Polypterus (Fig 1) is a tetrapodomorph precursor, related to lungfish in the LRT.

Third: Actinopterygia is not a monophyletic clade.

“Many fossil specimens of ray-finned fish have been placed in ‘wastebasket’ genera, meaning that their position in early actinopterygian evolution is not fully understood.

Waste basket taxa = unable to ascertain interrelationships.

“Redescribing species in these genera using modern techniques like CT scanning is crucial in understanding more about evolutionary relationships of early actinopterygians.’

In practice, just the opposite. Workers need to look at a WIDE gamut of taxa to understand interrelationships. µCT can help, but the LRT uses every source of data for 495 fish taxa.

“This project focused on a specimen from the Carboniferous referred to the problematic genus Elonichthys.”

If you want to study interrelationships, don’t focus on one genus.

“The specimen is preserved in 3D and has good preservation across much of the skeleton. Key features like the ectopterygoid process and the morphology of the hyomandibula and lachrymal suggest an affinity to polypterids, filling in a conspicuous gap in the early history of this group.”

In the large reptile tree (LRT, 2338 taxa), Elonichthys (Figs 2, 3) is in the ancestral lineage of Polypterus (Fig 1), but separated by several clades.

“Beyond its evolutionary position, Elonichthys caudalis displays features which indicate it was an active predator. This is based on its large and numerous teeth and the presence of short, stubby, widely-spaced gill rakers”

Neither of the Elonichthys specimens tested in the LRT have large teeth (Figs 2, 3).
E caudalis may be different, and if so, then is it the same genus?

“Continued focus on redescription of ray-finned fishes reveals more about their evolution and diversification throughout the Carboniferous.”

That’s a platitude = a given = common knowledge. When you’re a freshman paleo worker, phrases like this come up often because you follow what others do. I was the same way. There is time for this student to grow.

“More specifically, this work further develops our understanding of evolutionary relationships between actinopterygians, enables more accurate estimations of divergence timings between groups, and provides information on the lifestyles of fish during that period.”

Unfortunately, these are more platitudes unrelated to Elonichthys and ray-fin fish interrelatioknships. Abstracts should contain breaking news.

References
Tumelty M 2025. Revisiting the Carboniferous radiation of ray-finned fish. Progressive Palaentology 2025 Edinburgh June 17–20 Abstract Booklet.
Progressive Palaeontology (ProgPal) is an annual conference organised by students for students, and is supported by the Palaeontological Association. This year we are excited to host ProgPal 2025 in the beautiful city of Edinburgh!

wiki/Elonichthys

Source: https://pterosaurheresies.wordpress.com/2025/06/22/progpal-2025-abstracts-tumelty-on-ray-finned-fish-radiation/