Chinese paleontologists have discovered a new species of armored, jawless fish that lived about 419 million years ago. Named Bataspis crux, the Early Devonian galeaspid had a bat-wing-shaped head shield that may have helped it glide efficiently through the water.
Bataspis crux belonged to Galeaspida, an extinct group of armored, jawless fish that lived in what is now China and northern Vietnam during the Silurian and Devonian periods.
Galeaspids occupy an important position near the base of the vertebrate family tree. Studying these ancient fish can help scientists understand the anatomical and ecological conditions that led to the evolution of jawed vertebrates.
“Galeaspids are an extinct group of jawless gnathostomes and one of the closest relatives of jawed vertebrates, so understanding their paleontology is critical to understanding the anatomical and ecological conditions in which modern jawed vertebrates arose,” said palaeontologist Philip Donoghue from the University of Bristol.
“Endemic to what is now China and northern Vietnam during the Silurian and Devonian periods, galeaspids were discovered relatively late compared with other stem-gnathostome groups. As a result, new species continue to be identified at a rapid pace.”
“However, most species described in recent years have been assigned to known morphotypes that were traditionally interpreted as benthic or nektonic animals, based on comparisons with living jawed vertebrates.”
“Yet galeaspids, like most extinct gnathostome groups, lack reliable living representatives that could help scientists interpret their ecology.”
Phylogenetic analysis placed Bataspis crux within the galeaspid family Tridenthespiidae, where it is closely related to the previously known genera Pterogonaspis and Tridenthespis.
“Using both parsimony-based and probabilistic methods of phylogenetic estimation, we identified Bataspis crux as a member of the family Tridenthespiidae within the order Eugaleaspiformes,” the paleontologists said.
Holotype of Bataspis crux. Scale bar – 1 cm. Image credit: Meng et al., doi: 10.1111/pala.70081.
The fossil remains of Bataspis crux were collected near Qujing in Yunnan Province, China, during the 1980s.
“The specimen is preserved in fine-grained yellow-gray sandstone from the Xishancun Formation, which dates to the early Lochkovian of the Early Devonian,” the researchers said.
“All specimens are permanently housed in the collections of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, where they are available for study.”
What sets Bataspis crux apart from other galeaspids is the shape of its head shield. Instead of the spikes, crests, or rounded domes seen in other members of the group, this species had two broad, wing-like projections extending from the rear of its skull.
To determine the function of the unusual head shield, the scientists created a digital three-dimensional model of the fish and used computer simulations to analyze water flow around its body.
The simulations showed that the bat-wing-shaped head shield produced an exceptionally high lift-to-drag ratio for a galeaspid.
Water flowed faster over the curved upper surface of the wing-like projections and more slowly beneath them. This pressure difference generated lift according to the same basic aerodynamic principle that enables airplane wings to fly.
“The morphology of Bataspis crux exceeds the range of phenotypic variation previously known in galeaspids,” the authors concluded.
“The unique morphological characteristics of this bat-like jawless fish resulted in a high lift-to-drag ratio at low angles of attack.”
“Our findings reveal the broad range of locomotor abilities available to galeaspids and other jawless gnathostomes. They also demonstrate that the absence of a flexible pair of fins was not a constraint on ecological diversity.”
The findings appear in the journal Palaeontology.
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Meng Xinyuan et al. 2026. Bataspis crux, a galeaspid (jawless stem-gnathostome) from the Lochkovian of Yunnan Province, with a bat-wing-shaped head shield for hydrodynamic efficiency. Palaeontology 69 (4): e70081; doi: 10.1111/pala.70081.
Source: www.sci.news