Paleontologists in China have unearthed and examined the superbly preserved fossilized remains of two lamprey species from the Jurassic Yanliao Biota. Their findings shed new light on the evolution of the feeding apparatus, the life cycle, and the historic biogeography of lampreys.
Life reconstruction of the lamprey Yanliaomyzon from the Jurassic Yanliao Biota, China. Image credit: Nice Vistudio / Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.
Lampreys, one of two living lineages of jawless vertebrates, have great weight in the study of vertebrate evolution.
They are characterized by their peculiar feeding behavior of eating blood or cutting off tissues from the hosts or prey to which they firmly attach via their toothed oral sucker.
In such a way, lampreys play a significant role in the aquatic ecosystem and, in some cases, where they are non-native, even bring tremendous loss to the fishery economy.
These jawless fishes have been in existence for approximately 360 million years but left an extremely patchy fossil record in the post-Carboniferous period, with only two species known from the Cretaceous period.
The two new lamprey species, Yanliaomyzon occisor and Yanliaomyzon ingensdentes, lived during the Jurassic period, between 163 and 158.5 million years ago, and were part of the Yanliao Biota.
Yanliaomyzon occisor was around 64 cm (25 inches) long, making it the largest fossil lamprey ever found.
These fossil lampreys were exquisitely preserved with a complete suite of feeding structures, including the well-developed movable biting plates on the tongue-like piston.
Life reconstruction of the Jurassic lamprey Yanliaomyzon. Image credit: Nice Vistudio / Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.
The specimens of Yanliaomyzon occisor were found in the Tiaojishan Formation in China’s Liaoning Province and in the corresponding layers of Nanshimen Village in Hebei Province. The specimens of Yanliaomyzon ingensdentes came from the Daohugou beds in Liaoning Province.
Both Yanliaomyzon occisor and Yanliaomyzon ingensdentes astonishingly resemble the pouched lamprey (Geotria australis), a large flesh eater that can even destroy the skull of teleost fish and now confined to the southern hemisphere.
Dr. Feixiang Wu, a paleontologist with the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences, and his colleagues suggest that the flesh-eating habit is likely ancestral for modern lampreys, rather than the blood-eating as traditionally noted nor the non-feeding habit.
“Our study resolved these Jurassic lampreys as the closest fossil relatives to living lampreys,” Dr. Wu said.
“Contrary to conventional wisdom that modern lampreys’ ancestors fed on blood, our study showed that these two Jurassic lampreys must be flesh eaters, which foreshadows the flesh-eating habit of the most recent common ancestor of modern lampreys.”
Jurassic lampreys from the Yanliao Biota, China: Yanliaomyzon occisor (a-e) and Yanliaomyzon ingensdentes (f-h). Image credit: Wu et al., doi: 10.1038/s41467-023-42251-0.
“The emergence of advanced teleost fishes with thinned scales by the Early Jurassic might have provided an important evolutionary opportunity for lampreys,” he added.
“With the enhanced feeding structures, Jurassic lampreys onward were able to grow sufficiently large to meet the energy requirement of the evolution of a ‘prolonged’ life cycle interposed by the metamorphosis stage and involved in dramatic environmental shifts.”
The authors suggest that living lampreys originated in the southern hemisphere during the Late Cretaceous epoch.
This contradicts the conventional wisdom that they originated in the northern hemisphere, where most living lamprey species can be found.
“This discovery clearly indicates that the living southern lampreys retain a feeding morphology that already arose in the Jurassic, and that modern lamprey phylogeny is now consistent with a southern hemisphere origin, combined with an adaptation to a carnivorous diet,” said Professor Philippe Janvier, a paleontologist at France’s National Museum of National History.
The findings appear in the journal Nature Communications.
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F. Wu et al. 2023. The rise of predation in Jurassic lampreys. Nat Commun 14, 6652; doi: 10.1038/s41467-023-42251-0
