Aysheaia model

A model of Aysheaia

Aysheaia was a primitive type of lobopod from the Cambrian Period of North America.


Fossils of Aysheaia have ten body segments, each holding a pair of spiked legs that possess six curved claws each.[1] The head segment has two grasping legs and six finger-like projections around the mouth. It grew to a maximum of six centimeters in length.


The body shape of Aysheaia is similar to that of modern velvet worms, and it may have been an early relative of that group[2] (although it does not possess jaws or antennae[3]). There are two known species, A. pendunculata and A. prolata.


Aysheaia was first described by Charles Walcott in 1911 from the Burgess Shale.[4] He soon realized its similarity with velvet worms, and the genus was assumed to be one for many years. In 1978, H. B. Whittington reclassified Aysheaia in the stem group that led to both velvet worms and tardigrades.[1] This placement was subsequently modified by other researchers,[3] and its exact classification beyond the lobopods is still uncertain.



Fossils of Aysheaia are often associated with sponge remains, and it is believed that it may have been a sponge grazer that clung to its food with its claws.[3]


  1. 1.0 1.1 Whittington, H. B. (16 November 1978). "The Lobopod animal Aysheaia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 284 (1000): 165–197. Bibcode:1978RSPTB.284..165W. doi:10.1098/rstb.1978.0061. JSTOR 2418243.
  2. Ramsköld, L. and J. Y. Chen. 1998. Cambrian lobopodians: morphology and phylogeny, p. 107-150. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Volume 29. Columbia University Press, New York.
  3. 3.0 3.1 3.2 Robison, R. A. (1985). "Affinities of Aysheaia (Onychophora), with Description of a New Cambrian Species". Journal of Paleontology (Paleontological Society) 59 (1): 226–235. JSTOR 1304837.
  4. Walcott, C. D. 1911. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(2): 109-144.