Paleontologists in China have identified a new species of armored, jawless fish from rocks around 419 million years old whose skull was shaped like the wing of a bat and whose unusual head made it an efficient glider through Devonian seas.
Life reconstruction of Bataspis crux. Image credit: Dinghua Yang.
Bataspis crux belongs to Galeaspida, an extinct group of jawless fishes that lived only in what is now China and northern Vietnam during the Silurian and Devonian periods.
Galeaspids sit near the base of the vertebrate family tree, making them important for understanding the origins of jawed animals.
“Galeaspids are an extinct group of jawless stem-gnathostomes that are among the closest relatives of jawed vertebrates, and so an understanding of their paleobiology is crucial to elucidating the anatomical and ecological condition from which living jawed vertebrates arose,” said University of Bristol paleontologist Philip Donoghue and his colleagues.
“Endemic during the Silurian and Devonian to modern-day China and North Vietnam, the galeaspid fossil record was discovered late compared to other groups of stem-gnathostomes and so the discovery of new species continues apace.”
“However, the majority of new species described in recent years have fallen into known morphotypes that have traditionally been interpreted as benthic or nektonic based on ecomorphological analogy to living jawed vertebrates.”
“Nevertheless, galeaspids, like most stem-gnathostomes, lack credible extant counterparts that might aid the interpretation of their ecology.”
The phylogenetic analysis placed Bataspis crux within a family of galeaspids called Tridensaspidae, as a close relative of two previously known genera, Pterogonaspis and Tridensaspis.
“Using parsimony and probabilistic methods of phylogeny estimation, we find strong support for Bataspis crux as a member of Tridensaspidae within Eugaleaspiformes,” the paleontologists said.
Bataspis crux, holotype. Scale bars – 1 cm. Image credit: Meng et al., doi: 10.1111/pala.70081.
The fossilized remains of Bataspis crux were collected in the 1980s near Qujing in China’s Yunnan province.
“The specimens are preserved in fine-grained yellow-gray sandstone, belonging to the Early Lochkovian (Early Devonian) Xishancun Formation,” the researchers said.
“All specimens are permanently housed and accessible for examination in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.”
What sets Bataspis crux apart is the shape of its headshield. Rather than the spikes, crests or rounded domes typical of other galeaspids, the species sported a pair of sweeping, membrane-like projections at the back of its skull.
To test what this headshield was actually for, the scientists built a digital 3D model of the fish and ran it through computer simulations of water flow.
The results showed that the batwing-shaped headshield gave Bataspis crux the highest lift-to-drag ratio ever measured for a galeaspid.
The simulations suggest the flow of water accelerated over the curved upper surface of the wing-like projections while moving more slowly beneath their flatter undersides, generating lift through the same basic principle that allows airplane wings to fly.
“Bataspis crux extends beyond the range of phenotypic variation known previously for galeaspids,” the authors concluded.
“The unique morphological features of this bat-like jawless fish result in a high lift-to-drag ratio when at low angles of attack.”
“Our results reveal the breadth of locomotor capabilities available to galeaspids and other jawless stem-gnathostomes, demonstrating that an absence of flexible paired fins was not an impediment to ecological diversity.”
The findings appear in the journal Palaeontology.
_____
Xinyuan Meng et al. 2026. Bataspis crux, a galeaspid (jawless stem gnathostome) from the Lochkovian of Yunnan with a batwing-shaped head adapted for hydrodynamic efficiency. Palaeontology 69 (4): e70081; doi: 10.1111/pala.70081
