- PERIOD |
- Cambrian
- Ordovician
- Silurian
- Devonian
- Carboniferous
- Permian
Hallucigenia sp.
Hallucigenia was found by Walcott (1911) from the Burgess Shale which is famous for yielding bizarre fauna of the Middle Cambrian 1).
"Hallucigenia refers to the bizarre and dream-like appearance of animal" 1), as its name suggests, Hallucigenia has an enigmatic form. Hallucigenia is a member of the "lobopodans", a group of ancient worms which possess pairs of leg-like extensions of body. The affinities of this group are controversial, may be a base group of Panarthropods or a stem group to modern Onychophorans (velvet worm) 2).
The length of Hallucigenia is between 0.5 and 3.0 cm 1), relatively small.
Hallucigenia has a worm-like body with 7 pairs of dorsal spines and also 7 pairs of slender legs terminated in a pair of claws. The neck has 2 or 3 pairs of slightly short appendages 2). The elongated head with a pair of simple eyes terminates with a mouth which has a radial array of aclerotized elements resemble to ones in targigrades 4).
Hallucigenia may have fed on sponges, or scavenged on decaying animal remains 2).
Hallucigenia was described as a genus of the Annelids (Polychaeta), but afterwards, it has redescibed and redifined as a new genus and a new family, not an annelid 1). Subsequently, it has been found that the not antero-posterior but also dorso-ventral orientations of Hallucigenia proposed until then are reversed 2).
Hallucigenia may have had a warning coloration on tips of its dorsal spines.
created in December 2014.
References:
- Conway Morris S (1977) A new metazoan from the Cambrian Burgess Shale of British Columbia. Palaeontology 20(3):623–640
- Hallucigenia sparsa - The Burgess Shale (Royal Ontario Museum)
- Siveter DJ, Briggs DEG, Siveter DJ, Sutton MD, Legg D (2018) A three-dimensionally preserved lobopodian from the Herefordshire (Silurian) Lagerstätte, UKR. Soc. open sci. 5:172101. (DOI:10.1098/rsos.172101).
- Smith M, Caron J (2015) Hallucigenia’s head and the pharyngeal armature of early ecdysozoans. [abstract] Nature 523, 75–78. (DOI:10.1038/nature14573).