Antennacanthopodia

Antennacanthopodia Temporal range: Cambrian Stage 3 PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
(unranked):	Panarthropoda
Stem group:	Onychophora
Genus:	† Antennacanthopodia Ou et al., 2011 [1]
Species:	†A. gracilis
Binomial name
†Antennacanthopodia gracilis Ou et al., 2011 [1]

Antennacanthopodia is a small, onychophoran-like lobopod from the Chengjiang biota that dates to around 520 million years ago (Cambrian Stage 3). It has nine pairs of stubby legs, a pair of potential ocelli, and two pairs of antennae. The first pair of antennae are much longer that the second and are present in modern onychophorans. The identity of the smaller antennae are less clear, but they might be homologous with slime papillae. The animal also has a straight, voluminous midgut, diminutive spines on the legs and the trunk, well-developed leg musculature, highly sclerotised foot pads, and possible pair of appendicules at the end of its body. ^[1]

Discovery and naming

Both fossils of Antennacanthopodia were excavated from the upper Yu'anshan Member of the Lower Cambrian Heilinpu Formation. ^[1] This is close to the famous Maotianshan Shales of China’s Yunnan Province and probably makes them a part of the Chengjiang Biota. ^[1]

The holotype (ELEL-EJ081876) was collected from the Erjie section of the Yu'anshan Member's Eoredlichia-Wutingaspis Biozone while the paratype (ELI-JS022643) was found in the Jianshan section. ^[1] Both specimens date to around 520 million years old, placing them in the Cambrian Series 2 Stage 3. ^[1]

The genus gets it's name from the Latin words "antennatus" and "acanthopodus", referring to the fossil's multiple antennae and spiny lobopods. The species name is from the Greek "gracilis" meaning "slender" or graceful". ^[1]

Classification

Among other lobopods, Antennacanthopodia is frequently placed in a small clade that leads to modern onychophorans. ^{[2] [3] [4] [5]} This happens regardless of the position of Helenodora , as its identity as an onychophoran is contested. ^[6]

Add clade from source 3, 5, and 6

References

1. Qiang Ou; Jianni Liu; Degan Shu; Jian Han; Zhifei Zhang; Xiaoqiao Wan; Qianping Lei (2011). "A rare onychophoran-like lobopodian from the Lower Cambrian Chengjiang lagerstätte, southwestern China, and its phylogenetic implications". Journal of Paleontology . 85 (3): 587–594. Bibcode:2011JPal...85..587O. doi:10.1666/09-147R2.1. S2CID   53056128.
2. Smith, Martin R.; Ortega-Hernández, Javier (2014-10-17). "Hallucigenia's onychophoran-like claws and the case for Tactopoda". Nature. 514 (7522): 363–366. doi:10.1038/nature13576. ISSN   1476-4687.
3. Smith, Martin R.; Caron, Jean-Bernard (2015-07-02). "Hallucigenia's head and the pharyngeal armature of early ecdysozoans". Nature. 523 (7558): 75–78. doi:10.1038/nature14573. ISSN   1476-4687.
4. Zhang, Xi-Guang; Smith, Martin R.; Yang, Jie; Hou, Jin-Bo (2016-09-01). "Onychophoran-like musculature in a phosphatized Cambrian lobopodian". Biology Letters. 12 (9): 20160492. doi:10.1098/rsbl.2016.0492. PMC   5046927 . PMID   27677816.
5. Caron, Jean-Bernard; Aria, Cédric (2017-01-31). "Cambrian suspension-feeding lobopodians and the early radiation of panarthropods". BMC Evolutionary Biology. 17 (1): 29. doi:10.1186/s12862-016-0858-y. ISSN   1471-2148. PMC   5282736 . PMID   28137244.
6. Murdock, Duncan J. E.; Gabbott, Sarah E.; Purnell, Mark A. (2016-01-22). "The impact of taphonomic data on phylogenetic resolution: Helenodora inopinata (Carboniferous, Mazon Creek Lagerstätte) and the onychophoran stem lineage". BMC Evolutionary Biology. 16 (1): 19. doi:10.1186/s12862-016-0582-7. ISSN   1471-2148. PMC   4722706 . PMID   26801389.