Banfiidae is a family of extinct banffozoan animals from North America and China. The family name is sometimes spelt Banffidae. It includes Banffia, Heteromorphus, and possibly Skeemella. The family may be paraphyletic. A Heteromorphus-like dwarf "Form A" is allied with this group at the class level, but has not been formally described or assigned to this family.

Description

Banffiids have a bipartite body with a smooth anterior part that may or may not have a lateral groove, and a posterior part with many segments. Lateral pouches have not been seen, although some questions remain regarding their possible presence in Skeemella. The entire body is twisted dextrally (from an anterior view). Gut diverticula may be present, but the structures interpreted as such could alternatively be a circulatory system. The anus is terminal, despite initial reports to the contrary in Heteromorphus.

Distribution

Banffiids have been found across multiple paleocontinents, with Heteromporphus found in the Chengjiang lagerstatte of South China while Banffia has been found in the Burgess Shale and Spence Shale of western Laurentia. Skeemella has been found in the Pierson Cove and Marjum Formations, both above the Wheeler Shale and also in western Laurentia.

Taxonomy

The family Banffiidae and the class Banffozoa were proposed in a paper published in 2006, in order to contain Banffia constricta in a redescription of that species, with Heteromorphus only mentioned as a possible home outside of Banffiidae for Banffia confusa. A comprehensive phylogenetic revision in 2007 expanded Banffozoa to encompass the proposed class Heteromorphida (which had excluded Banffia), and placed Heteromorphus in the Banffiidae. It tentatively placed Skeemella outside of Banffiidae and the newly-erected order Banffiata, but under Banffozoa. "Form A", which had been included in the Heteromorphida, was not mentioned or reassigned. Two later sources have placed Skemella in Banffiidae while continuing to note doubts as to whether it is actually a vetulicolian.

Banffozoans have been recognized as "rather different from vetulicolians proper," and proposed to be more closely related to protostomes. However, multiple sources treat Banffozoa as part of Vetulicolia.

Cladograms

A 2024 study has found the Banffiidae to form the earliest part of the paraphyletic stem-chordate evolutionary grade, as shown in this simplified cladogram:

Chordata Banffia† Heteromorphus† Skeemella† Nesonektris† Vetulicolidae† Didazoon† Pomatrum† Yuyuanozoon† Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group) (total group)"Banffiidae" "Banffiidae" ?
ChordataBanffia† Heteromorphus† Skeemella† Nesonektris† Vetulicolidae† Didazoon† Pomatrum† Yuyuanozoon† Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group)
Banffia†
Heteromorphus†
Skeemella† Nesonektris† Vetulicolidae† Didazoon† Pomatrum† Yuyuanozoon† Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group)
Skeemella†
Nesonektris† Vetulicolidae† Didazoon† Pomatrum† Yuyuanozoon† Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group)
Nesonektris†
Vetulicolidae† Didazoon† Pomatrum† Yuyuanozoon† Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group)
Vetulicolidae†
Didazoon† Pomatrum† Yuyuanozoon† Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group)
Didazoon†
Pomatrum†
Yuyuanozoon†
Yunnanozoon† Cathaymyrus† Pikaia† Chordata (crown group)
Yunnanozoon†
Cathaymyrus† Pikaia† Chordata (crown group)
Cathaymyrus†
Pikaia†
Chordata (crown group)
(total group)

An earlier study in 2014 placed vetulicolians as the sister-group of tunicates, but was unable to resolve any relationships among vetulicolians as a group:

Vetulicolia†Vetulicola† Beidazoon† Ooedigera† Pomatrum† / Xidazoon† Didazoon† Yuyuanozoon† Banffia† "Banffiidae" Heteromorphus† Nesonektris†
Vetulicola†
Beidazoon†
Ooedigera†
Pomatrum† / Xidazoon†
Didazoon†
Yuyuanozoon†
Banffia†"Banffiidae"
Heteromorphus†
Nesonektris†
Tunicata

Works cited

  • 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:. S2CID .
  • Caron, Jean-Bernard (2006). "Banffia constricta, a putative vetulicolid from the Middle Cambrian Burgess Shale". Transactions of the Royal Society of Edinburgh: Earth Sciences. 96 (2): 95–111. doi:.
  • Chen, Ailin; Feng, Hongzhen; Zhu, Maoyan; Ma, Dongsheng; Li, Ming (2003). "A New Vetulicolian from the Early Cambrian Chengjiang Fauna in Yunnan of China". Acta Geologica Sinica. 77 (3): 281–287. doi:. S2CID .
  • García-Bellido, Diego C.; Lee, Michael S. Y.; Edgecombe, Gregory D.; Jago, James B.; Gehling, James G.; Paterson, John R. (2014). . BMC Evolutionary Biology. 14: 214. doi:. PMC . PMID .
  • Gee, Henry (July 4, 2018). Across the Bridge: Understanding the Origin of Vertebrates. University of Chicago Press. ISBN 978-0226402864.
  • 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:.
  • Kimmig, Julien; Leibach, Wade W.; Lieberman, Bruce S. (May 30, 2020). "First occurrence of the problematic vetulicolian Skeemella clavula in the Cambrian Marjum Formation of Utah, USA". Carnets Geology. 20 (10): 215–221. doi:. hdl:.
  • 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:. hdl:.
  • Mussini, G.; Smith, M. P.; Vinther, J.; Rahman, I. A.; Murdock, D. J. E.; Harper, D. A. T.; Dunn, F. S. (2024). . Current Biology. 34 (13): 2980–2989.e2. doi:. hdl:. PMID .
  • Shu, Degan (October 2005). . Chinese Science Bulletin. 50: 2342–2354. doi:.