A new snail amber with horny hair appeared 100 million years ago

 A new snail amber with horny hair appeared 100 million years ago

On October 12, a team of Chinese and foreign scientists announced that they had discovered for the first time in amber terrestrial snails with keratinous hairs, the oldest record of hairy structures in the current gastropods fossil record.

The study was conducted by Dr. Thomas A. Neubauer of Gisenius-Liebig University in Germany, Associate Professor Xing Lida of China University of Geosciences (Beijing) and Adrienne Jochum, a researcher at the Berne Museum of Natural History in Switzerland. The research papers were published in iScience, a well-known international academic journal and cell group.

Restoration map of Amber hairy snail. (Drawing Liu Yi)

The hairy shell is an ancestral sign.

The newly discovered snail amber fossils are about 6.6 mm in diameter and 2.2 mm in height. By reconstructing, segmenting and fusing CT data, Xing Lidas team obtained the high-definition 3D shape of the specimens.

Unlike most known gastropods, the shell is covered with dense cuticle hairs, and the upper and top edges of the spiral layer have obvious threads. Therefore, the author named a new genus Hirsuticyclus and a new species H. electrum.

In taxonomy, Amber snails belong to Cyclophoridae, Thomas pointed out. This family is some of the older terrestrial species, and generally prefers to live in warm, humid, dark and humic environment.

Like snails, most gastropods have a spiral shell that retracts the soft body when in danger. Some of the gastropods have a layer of keratinous hairs on their shells. For these hairy structures, scholars believe that it may be a defensive measure to reduce prey, or to increase water attachment to make movement more convenient, or to improve the adhesion of the shell surface.

This feature has been repeated in Hygromiidae and Helicidae, which indicates that it has evolved independently several times. Scholars speculate that the wool structure is an ancestor and has been lost many times in the history of evolution, which may be related to the round-trip transformation of the large environment from humidity to drought.

The fur on the shell can deter predators

Although wool structures have evolved independently several times, they have never been found in fossil records before, according to Xing Lida. We cant imagine that these exquisite structures can be preserved in the form of traditional fossils, but the emergence of amber perfectly solves this problem, giving us a chance to study the snails in the fossil record at last.

He said that the amber hairy snail is the magic gift of the special preservation of amber. It is the only record of hairy structure in the current gastropods fossil record and the oldest record.

What is the function of the cuticle covering the surface of the shell? Scientists believe that this cuticle is a snails adaptation to tropical forest environments, increasing its adhesion to plants during foraging in moist environments, and possibly carrying the function of collecting and transporting small seeds. The appearance of this trait is closely related to the global radiation evolution of angiosperms, the main food of snails. Snails may prefer soft angiosperms to hard conifers.

Scientists speculate that the amber snail has gradually adapted to the mid-Cretaceous angiosperm-dominated world. Its shell hairs first played a deterrent role to predators, and functionally helped it better attach to the leaves of angiosperms, reducing the risk of accidental drops and a large amount of wastage when it fell back to high places.

In addition, a thick layer of hair can also play a role in insulation.

Another interesting finding is that living bees unintentionally transfer pollen from one flower to another through their villi, and that the bristles of Amber snails may have similar functions.

In the mid-Cretaceous, the average size of angiosperm seeds was very small, often less than 1 cubic millimeter. The hairs of Amber snails might attach to some small seeds and spread as they moved to other locations.

Polychaete cricoccus. (Photography Zhou Tsinghua)

Know more: Amber is an excellent sample for paleontology research

In 2016, Xing Lidas team published the worlds first examples of ancient birds and dinosaurs in amber, followed by the discovery of frogs, snakes and snails with soft tissues such as antennae in amber.

Amber-encapsulated small animal fossils in Myanmar are the best Cretaceous paleontological samples we have ever encountered. They provide an important supplement to compacted fossils in sedimentary rocks, reveal three-dimensional details of soft tissues that are difficult to preserve in traditional fossils, and deepen our understanding of paleontology. Xing Lida introduced.

The Hukang Valley, a famous amber producing area in northern Kachin State of Myanmar, has been discovered successively since 2000. It also provides a unique record of forest ecosystem for scientists to study.

Just yesterday, paleontologists announced the results of their research on frog eggs amber. Specimens of amphibian eggs are extremely rare. Fifty-five spherical to ovoid eggs with an average diameter of about 1.2 mm were preserved. Each egg cell consists of a gelatinous mass and a dark central body, which may represent the original egg cell.

Wang Jun, reporter of Beijing News

Editor Fan Yiji proofread Li Xiangling

Source: New Beijing Daily Responsible Editor: Yao Liwei_NT6056