a catfish from the Silurian with preserved barbels (Figs. 1, 2).
catfish are members of the order Siluriformes (from ‘silurus’ Latin = large river fish). Previous oldest member of this clade: Late Cretaceous, 100mya. Sir Roderick Murchison (1792–1871), a wealthy Scottish aristocrat, named the Silurian Period after an ancient Welsh Celtic tribe, the Silures. Appears to be a coincidence. The slow genesis of plants and arthropods on land occurred in the Silurian, along with a rise in oxygen levels, a rise in temperature and a rise in sea levels after the massive glaciation of the Ordovician.
Not sure what the museum number is on this one.
In the large reptile tree (LRT, 1602 taxa; subset Fig. A) this taxon is labeled ‘unnamed Sil. catfish‘ (in the purple clade). In the LRT the new taxon is not as primitive as the armored catfish, Hoplosternum. Worthy of note, basal catfish in the LRT are air breathers employing the intestine or modified gill arches, not their air bladder, which they need to swim upright. Clarias is the famous walking catfish (Figs. 3–5) able to traverse land in search of other ponds. The spiny pectoral fins (Fig. 4) keep it upright and act as ground undulates as it wriggles from pond to pond.
The identity of this specimen
might have been overlooked because it appears like a silhouette, offering little detail. Digital Graphic Segregation (DGS) enables details to be colored, identified and later scored in the LRT.
Extant velvet catfish,
members of the clade Diplomystidae, are considered primitive.
Clarias batrachus (Linneaus 1758, up to 50 cm in length) is the extant walking catfish. The skull bones are nearly identical to those in the placoderm, Entelognathus. The spiny pectoral fins keep the walking catfish upright as it wriggles from pond to pond. No scales or bones appear on the surface. The teeth are short bristles on pads. The maxilla is absent.
Generally recognized fossil catfish
include Qarmoutus hitanensis from the same Eocene North African beds as the early whale, Basilosaurus. Reported by NatGeo.com (citation below): “Even though the fossil is relatively old in the way we ordinarily think of ages in millions of years, it is still essentially anatomically modern and directly comparable to living catfishes,” says John Lundberg of Drexel University’s Academy of Natural Sciences. “It’s one of the best preserved and oldest of its family.”
Afterthought about fish with spines in their fins
Spiny sharks (Acanthodii), like Brachyacanthus (Fig. 6), also briefly appeared in the Silurian and Devonian. Since the walking catfish uses its spiny fins to ‘walk’ on land, I wonder if spiny sharks, especially those with longer, thinner pectoral and pelvic spines, did the same, perhaps on the sea floor, not on land?
That might explain
why those extra spines appeared between the pectoral and pelvic fins, as extra hooks in the substrate?