| Revision as of 22:04, 13 December 2024 editIxat totep (talk | contribs)Extended confirmed users2,084 edits Tweak caption further- agree that "dwarf" without explanation was puzzling. But I should not have said "in the background" b/c "Form A" is very small, and this image is actually showing it at the same depth-of-field and scale as F. longicaudatus. Attempted to capture that, further improvements welcome.← Previous edit | Revision as of 22:07, 13 December 2024 edit undoIxat totep (talk | contribs)Extended confirmed users2,084 edits Match "review" from previous sentence- "source" had not been used so it was a bit unclear in context what "same source" was intended.Next edit → | ||
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| ===''H. confusus'' vs ''H. longicaudatus''=== | ===''H. confusus'' vs ''H. longicaudatus''=== | ||
| ''H. confusus'' was originally described as ''] confusa'' in 1997, while ''H. longicaudatus'' was described and assigned to the new genus ''Heteromorphus'' in 1999. The discoverers of ''B. confusa'' referred to it as ''H. confusus'' in 2002, accepting its assignment to ''Heteromorphus'' and, according to a comprehensive 2007 review of vetulicolian phylogenetics, indicating that ''H. longicaudatus'' is its junior synonym. However, the same |
''H. confusus'' was originally described as ''] confusa'' in 1997, while ''H. longicaudatus'' was described and assigned to the new genus ''Heteromorphus'' in 1999. The discoverers of ''B. confusa'' referred to it as ''H. confusus'' in 2002, accepting its assignment to ''Heteromorphus'' and, according to a comprehensive 2007 review of vetulicolian phylogenetics, indicating that ''H. longicaudatus'' is its junior synonym. However, the same review also noted substantial variation among ''Heteromorphus'' specimens, and that more species (including a distinct ''H. longicaudatus'') may exist.<ref name=Aldridge2007 /> | ||
| ==References== | ==References== | ||
Revision as of 22:07, 13 December 2024
Extinct genus of Cambrian organisms
| Heteromorphus Temporal range: Cambrian Stage 3 PreꞒ Ꞓ O S D C P T J K Pg N Cambrian Stage 3 | |
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| Artist's reconstruction of Heteromorphus longicaudatus (with much smaller "Form A" above it) | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade?: | †Vetulicolia |
| Class: | †Banffozoa |
| Order: | †Banffiata |
| Family: | †Banffiidae |
| Genus: | †Heteromorphus Luo and Hu in Luo et al. 1999 |
| Type species | |
| †Heteromorphus longicaudatus Luo and Hu in Luo et al. 1999 | |
| Species | |
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Heteromorphus is an extinct genus of banffid from the lower Cambrian Chengjiang lagerstatte. It contains one broadly accepted species, Heteromorphus confusus, as well as a proposed junior synonym, Heteromorphus longicaudatus that may prove to be a separate species as additional specimens are examined. A much smaller species labeled "Form A" is allied with Heteromorphus at the class level but has not been formally described or assigned to Heteromorphus itself.
Description
Like Banffia, Heteromorphus has a two-part body with a notable constriction between the parts, and a crossover that effectively reverses the dorsal and ventral sides between the anterior and posterior sections. The posterior portion is segmented, although the common presence of wrinkling makes counting the segments difficult. The anterior body shape ranges from torpedo-like to more rectangular, with a near-vertical anterior edge.
Heteromorphus is separated from Banffia by the presence of a lateral groove, similar to that found in the Vetulicolida. However, while a 2004 description claimed that four gill openings were present in the groove, later workers have not observed them. The lack of visible gills in banffids has been speculated to indicate a burrowing lifestyle. A partial "twist" has been described in Heteromorphus, compared to the well-developed torsion in Banffia. While the initial description of H. confusus indicated an anus halfway along the ventral surface of the posterior section, later descriptions confirmed the terminal location of the anus.
Taxonomy
Heteromorphus has been grouped with Banffia and Skeemella in the family Banffidae.
The following cladogram is simplified from Mussini et al. (2024), using the definition of Vetulicolidae from Li et al. (2018). It shows Heteromorphus as part of the earliest steps, corresponding to the class Banffozoa, in the evolutionary grade leading to extant chordates.
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"Banffozoa" "Vetulicolida" |
An earlier study in 2014 was unable to resolve any relationships among vetulicolians as a group:
| Vetulicolia† |
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H. confusus vs H. longicaudatus
H. confusus was originally described as Banffia confusa in 1997, while H. longicaudatus was described and assigned to the new genus Heteromorphus in 1999. The discoverers of B. confusa referred to it as H. confusus in 2002, accepting its assignment to Heteromorphus and, according to a comprehensive 2007 review of vetulicolian phylogenetics, indicating that H. longicaudatus is its junior synonym. However, the same review also noted substantial variation among Heteromorphus specimens, and that more species (including a distinct H. longicaudatus) may exist.
References
- ^ Aldridge et al. 2007, pp. 147–150
- McMenamin 2019, p. 8
- Conway Morris et al. 2015, pp. 3–4
- ^ García-Bellido et al. 2014, p. 9
- Chen & Zhou 1997, p. 86, Figure 138 caption
- Hou et al. 2017, p. 272
- Li et al. 2018, pp. 1083–1084
- Mussini et al. 2024, pp. 6–7
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:10.1111/j.1475-4983.2006.00606.x. S2CID 85722738.
- Chen, Junyuan; Zhou, Guiqing (1997). "Biology of the Chengjiang fauna". Bulletin of the National Museum of Natural Science. 10: 11–105.
- Conway Morris, Simon; Halgedahl, Susan L.; Selden, Paul; Jarrard, Richard D. (2015). "Rare primitive deuterostomes from the Cambrian (Series 3) of Utah" (PDF). Journal of Paleontology. 89 (4): 631–636. doi:10.1017/jpa.2015.40.
- García-Bellido, Diego C.; Lee, Michael S. Y.; Edgecombe, Gregory D.; Jago, James B.; Gehling, James G.; Paterson, John R. (2014). "A new vetulicolian from Australia and its bearing on the chordate affinities of an enigmatic Cambrian group". BMC Evolutionary Biology. 14: 214. doi:10.1186/s12862-014-0214-z. PMC 4203957. PMID 25273382.
- 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.
- McMenamin, Mark A. S. (2019). "Cambrian Chordates and Vetulicolians". Geosciences. 9 (8): 354. Bibcode:2019Geosc...9..354M. doi:10.3390/geosciences9080354. ISSN 2076-3263.
- 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. doi:10.1016/j.cub.2024.05.026. PMID 38866005.
- Shu, Degan (2005). "On the Phylum Vetulicolia". Chinese Science Bulletin. 50 (20): 2342–2354. Bibcode:2005ChSBu..50.2342S. doi:10.1007/BF03183746. S2CID 86827605.