A ‘Worthless’ Fossil Fills A 50-Million-Year Gap In The Fish Family Tree

Scientists Find a New Species in a London Museum Drawer: It’s Been There Since 1885

Paleontologists have long known coelacanths as one of nature’s great comeback stories. Considered extinct for 66 million years, these ancient lobe-finned fish turned up alive in a South African fishing net in 1938. Their living representative, Latimeria, belongs to a family stretching back more than 200 million years, yet no confirmed fossils from that family had been found in the Lower Cretaceous, leaving a roughly 50-million-year hole in the record. That gap just got filled by a skull sitting unidentified in a London museum drawer for nearly 140 years.

Researchers recently identified the specimen as an entirely new species: Macropoma gombessae, the oldest known member of its genus and the first diagnostic member of the living coelacanth’s family from the Lower Cretaceous. The fossil was purchased by what is now the Natural History Museum in London in 1885 from dealer John Starkie Gardner and had never been formally described or cited in scientific literature.

Its species name is a nod to the communities who knew the coelacanth long before Western science caught up. “Gombessa” is the word used by Malagasy communities and fishermen of the Comoros Islands for the living coelacanth, meaning “inedible fish” or “worthless fish.” That a specimen overlooked for over a century now bears that name feels fitting, because this fossil is anything but worthless.

How Researchers Dated the Coelacanth Fossil

Collected from marine clay deposits near Folkestone in Kent, the fossil’s exact spot within the formation is somewhat uncertain. To establish when this animal lived, the team analyzed tiny marine organisms in the surrounding rock, placing the specimen in the middle to late Albian stage of the Lower Cretaceous, about 100 to 113 million years ago. That dating slots it directly into the previously empty gap.

CT scanning provided the real breakthrough. Using a high-powered X-ray scanner at the Natural History Museum, the researchers digitally stripped away the encasing mudstone for a full 360-degree view. About five hours of scanning collected more than 4,000 individual projections, processed with specialized software to isolate individual bones.

What emerged was a skull about four inches long, preserved on its side in mudstone. Most of the right side was exposed, along with parts of the skull roof, palate, and sections of the shoulder and pelvic area. The lower jaws had slipped forward slightly during fossilization and the body behind the head twisted into an S-shape, but preservation was good enough to reveal considerable detail.

Macropoma gombessae Showed Coelacanths Were Actively Evolving

Comparing the new species against its close relatives revealed a mix of familiar and clearly different features. The overall layout of bones on the skull roof resembled other Macropoma species, but the surface texture told a different story. While later relatives sport a bumpy, ridged pattern, Macropoma gombessae displays long ridges mixed with scattered oval pits. The authors describe this as “a drastic shift in dermal ornamentation between the Lower and Upper Cretaceous.”

Perhaps most telling was the lower jaw. In the living coelacanth, one of the front jaw bones has a distinctive hook-shaped projection that curves backward. Later Cretaceous species of Macropoma also have this hook, but it is more prominent. In Macropoma gombessae, that hook is smaller and more reduced, suggesting researchers were looking at a transitional stage in the jaw’s evolution toward the shape seen in living coelacanths today.

Another distinguishing feature involved the sensory canal system on top of the skull. In later Cretaceous species, tiny pores for this canal sit within each individual bone. In Macropoma gombessae, those pores are unusually large and sit at the boundary between neighboring bones, a placement not seen in other members of the genus.

New Fossil Places Coelacanths on the Branch Nearest Living Species

To figure out where this new species fits in the broader coelacanth family tree, the team ran a formal evolutionary analysis. Macropoma gombessae was placed as the closest relative to the other known Macropoma species, which together sit next to a branch containing Swenzia and the living Latimeria, though future finds could refine that picture. In plain terms, this fossil is on the branch just next door to the lineage that eventually produced today’s coelacanth.

Before this discovery, published in Papers in Palaeontology, the only supposed evidence of coelacanths in these rock formations rested on spiral-shaped fossilized droppings attributed to Macropoma since the 1820s. Researchers dismissed those identifications, noting that many Cretaceous fish groups could have produced them. Macropoma gombessae is the first confirmed body fossil of the genus in the Gault Formation.

Latimeriidae, the family containing both this fossil and the living coelacanth, is identified in the paper as the longest surviving extant family of jawed vertebrates, ranging from the Middle Triassic to the present. By plugging a 50-million-year gap with a single well-preserved skull, Macropoma gombessae fills in a major chapter and improves our understanding of how coelacanth evolution unfolded.

Measurable differences between this Lower Cretaceous species and its later relatives, from jaw shape to bone texture to sensory canal placement, also push back on the “living fossil” label. These fish were changing in real, traceable ways across tens of millions of years.

A “worthless fish” by name, maybe. But a fossil that reshapes a 200-million-year family history after gathering dust in a museum drawer for 140 years is about as far from worthless as it gets.

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