Olfactores is a clade within the Chordata that comprises the Tunicata (Urochordata) and the Vertebrata (sometimes referred to as Craniata).[3] Olfactores represent the overwhelming majority of the phylum Chordata, as the Cephalochordata are the only chordates not included in the clade. This clade is defined by a more advanced olfactory system which, in the immediate vertebrate generation, gave rise to nostrils.
| Olfactores | |
|---|---|
| |
| Example of Olfactores | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Olfactores Jefferies, 1991 |
| Subphyla | |
Etymology
editThe name Olfactores comes from Latin *olfactores ("smellers," from purposive supine olfactum of olfacio, "to smell," with plural masculine agentive nominalizing suffix -tores), due to the development of pharyngeal respiratory and sensory functions, in contrast with cephalochordates such as the lancelet which lack a respiratory system and specialized sense organs.[3]
Olfactores hypothesis
editThe long-standing Euchordata hypothesis that Cephalochordata is a sister taxon to Craniata was once widely accepted,[4] likely influenced by significant tunicate morphological apomorphies from other chordates, with cephalochordates even being nicknamed 'honorary vertebrates.'[5]
The name Olfactores was originally introduced in 1991 as part of the now-disproven calcichordate hypothesis.[6] However, studies since 2006 analyzing large sequencing datasets strongly support Olfactores as a clade.[7][8]
Anatomy of ancestral Olfactores
editSome studies suggest that the ancestors of Appendicularia and Vertebrata were possibly sedentary-pelagic,[9][10][11] although others recover a free-living chordate ancestor transitioning to free-living vertebrates without an intervening sedentary form.[12] A rudimentary neural crest is present in tunicates, implying its presence in the Olfactores ancestor also, as vertebrates have a true neural crest.[13]
References
editWorks cited
edit- Ax, P. (2001). Das System der Metazoa: ein Lehrbuch der phylogenetischen Systematik. Spektrum Akademischer Verlag. ISBN 978-3-437-30803-1.
- Benton, M.J. (14 April 2000). Vertebrate Palaeontology: Biology and Evolution. Blackwell Publishing.
- Delsuc, Frédéric; Brinkmann, Henner; Chourrout, Daniel; Philippe, Hervé (2006). "Tunicates and not cephalochordates are the closest living relatives of vertebrates" (PDF). Nature. 439 (7079): 965–968. Bibcode:2006Natur.439..965D. doi:10.1038/nature04336. PMID 16495997. S2CID 4382758.
- Delsuc, Frédéric; Philippe, Hervé; Tsagkogeorga, Georgia; Simion, Paul; Tilak, Marie-Ka; Turon, Xavier; López-Legentil, Susanna; Piette, Jacques; Lemaire, Patrick (2018-04-13). "A phylogenomic framework and timescale for comparative studies of tunicates". BMC Biology. 16 (39). doi:10.1186/s12915-018-0499-2. hdl:10261/163664. PMC 5899321.
- Dunn, C.W.; Hejnol, A.; Matus, D.Q.; Pang, K.; Browne, W.E.; Smith, S.A.; Seaver, E.; Rouse, G.W.; Obst, M.; Edgecombe, G.D.; Sørensen, M.V.; Haddock, S.H.D.; Schmidt-Rhaesa, A.; Okusu, A.; Kristensen, R.M.; Wheeler, W.C.; Martindale, M.Q.; Giribet, G. (2008). "Broad phylogenetic sampling improves resolution of the animal tree of life". Nature. 452 (7188): 745–749. Bibcode:2008Natur.452..745D. doi:10.1038/nature06614. PMID 18322464. S2CID 4397099.
- Fedonkin, M. A.; Vickers-Rich, P.; Swalla, B. J.; Trusler, P.; Hall, M. (2012). "A new metazoan from the Vendian of the White Sea, Russia, with possible affinities to the ascidians". Paleontological Journal. 46: 1–11. doi:10.1134/S0031030112010042. S2CID 128415270.
- Jeffries, R. P. S. (1991). "Two types of bilateral symmetry in the Metazoa: chordate and bilaterian". In Bock, Gregory R.; Marsh, Joan (eds.). Biological Asymmetry and Handedness. Ciba Foundation Symposium. John Wiley and Sons. doi:10.1002/9780470514160.ch7.
- Martynov, Alexander V.; Korshunova, Tatiana A. (2022-08-11). "Renewed perspectives on the sedentary-pelagic last common bilaterian ancestor". Contributions to Zoology. 91 (4–5): 285–352. doi:10.1163/18759866-bja10034. ISSN 1875-9866.
- Mussini, G.; Smith, M. P.; Vinther, J.; Rahman, I. A.; Murdock, D. J. E.; Harper, D. A. T.; Dunn, F. S. (2024). "A new interpretation of Pikaia reveals the origins of the chordate body plan". Current Biology. 34 (13): 2980–2989.e2. Bibcode:2024CBio...34.2980M. doi:10.1016/j.cub.2024.05.026. hdl:10141/623098. PMID 38866005.
- Nanglu, Karma; Lerosey-Aubril, Rudy; Weaver, James C.; Ortega-Hernández, Javier (2023-07-06). "A mid-Cambrian tunicate and the deep origin of the ascidiacean body plan". Nature Communications. 14 (1): 3832. doi:10.1038/s41467-023-39012-4. ISSN 2041-1723. PMC 10325964.
- Stach, Thomas (2008). "Chordate phylogeny and evolution: a not so simple three‐taxon problem". Journal of Zoology. 276 (2): 117–141. doi:10.1111/j.1469-7998.2008.00497.x.
- Yang, Chuan; Li, Xian-Hua; Zhu, Maoyan; Condon, Daniel J.; Chen, Junyuan (2018). "Geochronological constraint on the Cambrian Chengjiang biota, South China" (PDF). Journal of the Geological Society. 175 (4): 659–666. Bibcode:2018JGSoc.175..659Y. doi:10.1144/jgs2017-103. ISSN 0016-7649. S2CID 135091168.
- York, Joshua R.; McCauley, David W. (2020). "The origin and evolution of vertebrate neural crest cells". Open Biology. 10 (1) 190285. doi:10.1098/rsob.190285. PMC 7014683. PMID 31992146.