Marine life

Genomic Study Rewrites Shark Evolutionary Tree

Are sharks and rays products of shared evolution or were they designed as separate creatures from the start?

Published MAR 13

Genomic Study Rewrites Shark Evolutionary Tree

Story

Image credit: Unsplash

The Facts

A genomic study of 48 shark, ray and skate species analyzed two types of genetic data — protein-coding sequences and ultra-conserved regions — to examine the evolutionary relationships among cartilaginous fishes, known as Chondrichthyes.
Biorxiv
Nature
Protein-coding exons supported the traditional view that sharks form a monophyletic group, while ultra-conserved elements suggested sharks may be paraphyletic, with the shark family Hexanchiformes forming a lineage distinct from all other sharks, rays and skates.
Biorxiv
Nature
Hexanchiformes — which include cow sharks and frilled sharks — have six or seven gill slits instead of the usual five, along with primitive-looking jaws, and retain the ancestral jaw structure of cartilaginous fishes.
Biorxiv
Nature
Evolutionary biologists Thomas Near and Chase Brownstein of Yale University conducted the analysis, noting that if sharks are paraphyletic, rays and skates would effectively represent another form of shark, with the shark body plan emerging first.
Biorxiv
Nature
The study's time-calibrated phylogeny supports a Jurassic diversification of most sharks and a Cretaceous-Paleogene diversification of rays and skates, tying living cartilaginous fish diversity to shifts in marine ecosystems during the Mesozoic Era.
Biorxiv
Nature
Gavin Naylor, an evolutionary biologist at the Florida Museum of Natural History, noted that animals resembling modern sharks have existed for roughly 330 million years, and that "having an accurate phylogeny is a way forward for understanding the processes that have shaped life." The study hasn't yet been peer reviewed.
Biorxiv
Nature

Sources Split

LEFT

CENTER

RIGHT

ESTAB
CRIT

CENTER

PRO
ESTAB

The Spin

Narrative A

Genomic data is rewriting what's known about shark evolution, and the results are stunning — sharks may not even form their own distinct group depending on which genome markers get analyzed. The position of ancient lineages such as sixgill and frilled sharks throws the entire evolutionary tree into question. This isn't a minor footnote; it's a major unresolved issue in vertebrate science with real conservation stakes.

Chase Brownstein on X

Narrative B

No fossil evidence of a common ancestor for sharks and rays has ever been found, and the creatures themselves are radically different in body shape, breathing mechanics and movement. Grouping them together simply because both have cartilage instead of bone is not proof of shared ancestry — it's an assumption. The far more reasonable conclusion is that these distinct creatures were designed separately from the start.

Creation Ministries International (CMI)

Metaculus Prediction

Editor's Note

This story currently has limited coverage. We will continue to monitor all major outlets and update our reporting as additional information becomes available.