Tanazios

Tanazios is a genus of Silurian stem-mandibulate.

Tanazios Temporal range: Homerian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Genus:	†Tanazios Siveter et al, 2007
Species:	†T. dokeron
Binomial name
†Tanazios dokeron Siveter et al, 2007

Description

Tanazios has a head with five pairs of appendages, these being the antennae, antennules, mandibles with gnathobasic coxae and two biramous limb pairs similar to those of the trunk, with a large projection in the hypostome's centre. The trunk consists of 64 segments and has 60 appendage pairs, with a small telson on the end that holds the anus and a caudal ramus.^[1] Tanazios lacks second antennae, which character shared with hexapods.^[2]

Ecology

Tanazios has been proposed to be either a benthic or demersal scavenger.^[1]

Etymology

Tanazios is a combination of the words "tanaos", meaning "long", "zoon", meaning "animal" and "pelagios", meaning "of the sea". The species name dokeron is a combination of "dodeka" ("twelve"), "kerouchos" ("horned") and "epikranon" ("helmet").

Distribution

Tanazios is known from two reconstructed specimens from the Coalbrookdale Formation (as the concretions fossils are found in cannot be studied easily, fossils have to be reconstructed digitally via grinding then scanning them).

Classification

Tanazios was originally considered as stem-group crustacean.^[3] According to phylogenic analysis in Pulsipher et al. (2022), it is considered as stem-mandibulate instead.^[4]

Arthropoda	†Parioscorpio venator †Cascolus ravitis †Tanazios dokeron †Captopodus poschmanni †Acheronauta stimulapis †Thylacocephala †Occacaris oviformis Myriapoda †Ercaicunia multinodosa †Clypecaris pteroidea †Waptia fieldensis †Perspicaris dictynna †Canadaspis perfecta †Tokummia katalepsis †Branchiocaris pretiosa †Nereocaris exilis †Odaria alata †Euthycarcinoidea †Fuxianhuiida †Fuxianhuia †Chengjiangocaris †Shankouia Pancrustacea Argulus Ostracoda †Lepidocaris Triops Artemia Remipedia Cephalocarida Hexapoda Multicrustacea	Hymenocarina

References

1. Siveter, Derek J (3 July 2007). "A new probable stem lineage crustacean with three-dimensionally preserved soft parts from the Herefordshire (Silurian) Lagerstätte, UK". The Royal Society Publishing. doi:10.1098/rspb.2007.0429. PMC 2706188.
2. Budd, Graham E.; Telford, Maximilian J. (2009). "The origin and evolution of arthropods". Nature. 457 (7231): 812–817. doi:10.1038/nature07890. ISSN 1476-4687.
3. Siveter, David J.; Briggs, Derek E. G.; Siveter, Derek J.; Sutton, Mark D.; Legg, David (2017-03-29). "A new crustacean from the Herefordshire (Silurian) Lagerstätte, UK, and its significance in malacostracan evolution". Proceedings of the Royal Society B: Biological Sciences. 284 (1851): 20170279. doi:10.1098/rspb.2017.0279. ISSN 0962-8452. PMC 5378094. PMID 28330926.
4. Pulsipher, M. A.; Anderson, E. P.; Wright, L. S.; Kluessendorf, J.; Mikulic, D. G.; Schiffbauer, J. D. (2022). "Description of Acheronauta gen. nov., a possible mandibulate from the Silurian Waukesha Lagerstätte, Wisconsin, USA". Journal of Systematic Palaeontology. 20 (1). 2109216. doi:10.1080/14772019.2022.2109216. S2CID 252839113.