A PERFECT SPECIMEN OF THE LOWER CAMBRIAN ARTHROPOD FUXIANHUIA PROTENSA (CHENGJIANG)
Maria Angelica Muniz Frosi posted this text in the group "The Cambrian Period": 525 million years ago, this creature already had a brain and eyes. The animal, classified as Fuxianhuia protensa, is one of the first arthropods, ancestor of the current shrimps, insects or spiders e. g., and lived in the Cambrian period.
Phylum Arthropoda, Order Fuxianhuiida, Family Fuxianhuiidae
Geological Time: Lower Cambrian (~ 525 million years ago)
Fossil site: Chengjiang Maotianshan Shale, Quiongzhusi Section, Yu'anshan Member, Heilinpu Formation, Maotianshan, Yuxi, Chengjiang County, Yunnan Province, China
The classification of Fuxianhuia is one of the most disputed fossils of the site, with some considering eoarthropod. Chengjiang Biota founder and co-worker erected a new family and a new superclass called Proschizoramia, which was characterized as a group at any early stage in the evolution of arthropods with biramosis (Hou et al., 1987). Another initial analysis described as a trunk chelatorate group (Will, et al., 1996). More recently, Ma et al. (2012) suggested that the head, brain and optic lobes had characteristics similar to a malacostráceo (shrimp), chilopod and insect and, therefore, that Fuxianhuia could precede its evolutionary division.
Discovered by Hou Xian-guang in 1984, Chengjiang Biota is about 10 million years older than the Middle Cambrian Burgess Shale. Like the Burgess Shale, non-mineralized soft tissue parts are often remarkably well preserved with high resolution as aluminosilicate films, sometimes with oxidized iron content. Several taphonomic processes leading to extensive soft tissue preservation have been proposed, including rapid death by asphyxiation followed by rapid burial in anoxic sediment not disturbed by turbidity.
The Chengjiang biota is dominated by the Arthropoda and Porifera phyla. There are seven lobopodians, more than any other Lagerstätte that some scientists raise to the level of the phylum, and seven members of the extinct edge Vetulicolia. Members or potential members of Phyla Priapulida, Nematomorpha, Hyolitha, Hemichordata, Echinodermata, Ctenophora, Chordata, Cnidaria, Chaetognatha and Brachiopoda are found. A large number of enigmatic animals of uncertainty have also been found, some of which may represent failed evolutionary experiments, or even new phyla that did not persist for long at the beginning of the Cambrian, or were replaced by more derivative forms.
Among the diverse fauna of Maotianshan Shales, the most important are the supposed primordial chordates, particularly Haikouella, potentially an ancestor or the first cranial chordate. Myllokunmingia and Haikouichthys are interpreted as primitive Craniata, and possibly very primitive agnathids, the progenitor of fish and all vertebrates.
References:
Hou, X.-g (1987). "Three new large arthropods of the Lower Cambrian, Chengjiang, Eastern Yunnan [in Chinese]". Acta Palaeontolologica Sinica 26: 272-285
Chen, JY; Edgecombe, G. D .; Ramsköld, L; Zhou, L (1995). "Segmentation of the head at the beginning of the Cambrian Fuxianhuia: implications for the evolution of arthropods". Science 268 (5215): 1339-1343.
Wills, M.A.; Edgecombe, G. D .; Ramsk, L. (1996). "Arthropod Classification". Science 272 (5262): 746-747.
Ma, X; Hou, X; Edgecombe, G. D .; Strausfeld, N.J. (2012). "Complex brain and optical lobes in an early Cambrian arthropod". Nature 490 (7419): 258-261.
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