Members of the Vetulicolidae have relatively robust body coverings, with a subquadrate to elongate (in lateral view) anterior part and an elongate, segmented posterior part. The marginal zone of the anterior part may have short projections dorsally and postereodorsally.[2] As diagnosed by Aldridge et al. in 2007, the anterior part is said to bear five annulations, and a lateral groove is not mentioned for the family. However, with and the addition of Ooedigera not all genera possess annulations in the anterior section,[3] and with the re-classification of Yuyuannozoon[1] each genus currently assigned to this family bears a lateral groove.[4][5][6][3]
Vetulicolids range in size from Beidazoon (around 1 cm long) to Vetulicola (around 8 or 9 cm).[1]Ooedigera is in-between at a little over 4cm.[7] The anterior parts of Ooedigera and Beidazoon bear textural ornamentation.[8]
Distribution
Ooedigera is known from the Sirius Passet Lagerstätte in far northern Greenland, while Beidazoon is known only from the Chengjiang fauna. Vetulicola is known from the Chengjiang fauna, the Guanshan biota (both of the Maotianshan Shales of China), as well as the Mural Formation of the Canadian Rockies. The Banffozoa have a similar distribution, while the Didazoonidae are limited to the Maotianshan Shales.[1][2]
Taxonomy
The composition of the Vetulicolidae has seen several changes. Yuyuanozoon was at one point placed in the family,[9] but has since been moved to the Didazoonidae.<name=Li2018 /> Beidazoon was initialy placed in its own family, Beidazoonidae,[10] but its junior synonym Bullivetula was placed in the Vetulicolidae[11] and later authors have followed that placement.[1]
A 2024 study has found Vetulicolidae (as defined in a 2018 phylogeny)[1] to be a monophyletic group within a paraphyletic Vetulicolia, crownwards of Banffozoa and Nesonektris but basal to Didazoonidae. It is the only vetulicolian family that was recovered as a monophyletic clade:[12]
An earlier study in 2014 placed vetulicolians as the sister-group to tunicates, but was unable to resolve any relationships among vetulicolians as a group:[13]
Aldridge, Richard J.; Hou, Xian-guang; Siveter, David J.; Siveter, Derek J.; Sarah E., Gabbott (2007). "The systematics and phylogenetic relationships of vetulicolians". Palaeontology. 50: 131–168. doi:10.1111/j.1475-4983.2006.00606.x. S2CID85722738.
Hou, Xian-guang; Siveter, David J.; Siveter, Derek J.; Aldridge, Richard J.; Cong, Pei-yun; Gabbott, Sarah; Ma, Xiao-ya; Purnell, Mark A.; Williams, Mark (2017). "Vetulicolians". The Cambrian Fossils of Chengjiang, China: The Flowering of Early Animal Life (2 ed.). pp. 272–281. doi:10.1002/9781118896372.ch25.
Li, Yujing; Williams, Mark; Gabbott, Sarah E.; Chen, Ailen; Cong, Peiyun; Hou, Xianguang (2018). "The enigmatic metazoan Yuyuanozoon magnificissimi from the early Cambrian Chengjiang Biota, Yunnan Province, South China". Journal of Paleontology. 92 (6): 1081–1091. doi:10.1017/jpa.2018.18.