Hallucigenia, an animal lived in the Cambrian period, between 520 and 505 million years ago, has been considered for decades a really weird animal, hence the name. It looked like it could be part of a family that got extinct but the discovery of new fossils allowed to study it better since the ’90s. Now according to a new research carried out at the University of Cambridge hallucigenia, or rather the hallucigenia genus, is a lobopode, related to modern velvet worms, part of the Onychophora phylum.

The first species of hallucigenia was found in the Burgess Shale since 1911. Only after decades this animal was called hallucigenia sparsa (image ©Stanton F. Fink) and immediately speculation started about its classification. The first fossils were incomplete and in its early descriptions it was walking on its spines. According to another theory, it was a part of a larger animal.

New fossils of an animal called Microdictyon, which showed several similarities with hallucigenia, led to a new interpretation of the old fossils. In the new image, the animal was reversed: what were seen as legs became protections on the back and what were seen as tentacles became legs.

In the ’90s in the Maotianshan deposit in China another animal was found very similar to hallucigenia was found, so much that it was included in the same genus and called hallucigenia fortis. This species has spines much shorter than hallucigenia sparsa.

Hallucigenia was really small in size, between 0.5 and 3.5 cm, and this didn’t help the research. Now a team of researchers at the University of Cambridge has published in the journal “Nature” a study that illustrates the similarities between hallucigenia and the so-called velvet worms, modern Onychophora. They aren’t really worms but the name is due to their shape and are a small group of animals that live in tropical forests.

In particular, the study of hallucigenia’s claws was considered the main evidence of its relationship with velvet worms. They were never studied in detail and only now several similarities in the structure of the claws of these two animals lived so far away were highlighted.

It’s possible that the velvet worms are descendants of hallucigenia. This type of research may shed light on the classification of very ancient animals in this way can also help to better understand the evolution of other groups of animals such as the arthropods, which are related to the Onychophora.

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