A new species of 'super-armoured' worm, a bizarre, spike-covered creature which ate by filtering nutrients out of seawater with its feather-like front legs, has been identified by palaeontologists. The creature, which lived about half a billion years ago, was one of the first animals on Earth to develop armour to protect itself from predators and to use such a specialised mode of feeding.
The creature, belonging to a poorly understood group of early animals, is also a prime example of the broad variety of form and function seen in the early evolutionary history of a modern group of animals that, today, are rather homogenous. The results, from researchers at the University of Cambridge and Yunnan University in China, are published today (29 June) in the journal PNAS.
The creature has been named Collinsium ciliosum, or Hairy Collins' Monster, named for the palaeontologist Desmond Collins, who discovered and first illustrated a similar Canadian fossil in the 1980s. The newly-identified species lived in what is now China during the Cambrian explosion, a period of rapid evolutionary development around half a billion years ago, when most major animal groups first appear in the fossil record.
A detailed analysis of its form and evolutionary relationships indicates that the Chinese Collins' Monster is a distant early ancestor of modern velvet worms, or onychophorans, a small group of squishy animals resembling legged worms that live primarily in tropical forests around the world.
"Modern velvet worms are all pretty similar in terms of their general body organisation and not that exciting in terms of their lifestyle," said Dr Javier Ortega-Hernández of Cambridge's Department of Earth Sciences, one of the paper's lead authors. "But during the Cambrian, the distant relatives of velvet worms were stunningly diverse and came in a surprising variety of bizarre shapes and sizes."
Cambrian lobopodians: A review of recent progress in our understanding of their morphology and evolution
Authors:
Liu et al
Abstract:
Lobopodians are an important group of organisms which appeared during the Cambrian Explosion. The underlying morphology is invariably a worm-like body bearing multiple pairs of legs. Yet in detail these animals preserve a range of morphologies and have attracted much paleontological attention; particularly since this assemblage probably includes the ancestors of living velvet worms (Onychophora), water bear (Tardigrada) and arthropods (Arthropoda). In recent years, knowledge of Cambrian lobopodians has increased dramatically based on numerous new records. However, there have been few comprehensive reviews of these animals since Ramsköld & Chen's study in 1998. In the present paper, new insights into Cambrian lobopodians are presented. The legs of Aysheaia pedunculata have a strong attachment with the body, like those of lobopodians in the Chengjiang Fauna. Hallucigenia fortis has a pair of eyes, two pairs of tentacles are observed in the ‘neck’ region while a bivalved head shield is unequivocally lacking. Some new characters for, and the orientation of, Hallucigenia sparsa are discussed. Longitudinal wrinkles on the body of Xenusion auerswalde are regarded here as putative muscles. Cardiodictyon sinicum bears doublure structures at the anterior margin of head and a pair of eye spots; the shape of dorsal plates is also reinterpreted. Onychodictyon has a pair of anterior appendages, but no sclerotized head shield. The affinities of Miraluolishania haikouensis are clarified and the proposal that M. haikouensis is a junior synonym of Luolishania longicruris is refuted. The large lobopodians, Kerygmachela, Jianshanopodia and Megadictyon – all with frontal appendages, gill-like limbs and tree-like or lamellate-like branches – may be swimming predators.
Link in title.
