Bifurculapes
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Edward Hitchcock erected the ichnogenus Bifurculapes, meaning "two little forked feet," for trace fossils that were discovered in the Early Jurassic Turners Falls Formation in the Deerfield Basin of Massachusetts.[1] They are insect or crustacean trackways that consist of two rows of two to three tracks per series, with the two larger tracks being oriented parallel or oblique to the trackway axis. The third track, when present, is much smaller than the other two and is oriented approximately perpendicular to the trackway axis. Medial drag marks sometimes are present between the track rows. In trace fossil classification schemes based on behavior, Bifurculapes is considered a repichnion, or locomotion trace. Getty (2020) considered Bifurculapes to represent locomotion under water based on the orientation of some trackways relative to sedimentary structures called current lineations.[2]
Hitchcock originally erected four ichnospecies, B. elachistotatus, B. laqueatus, B. scolependroideus, and B. tuberculatus, but subsequently removed B. tuberculatus while erecting B. curvatus.[3] Since Hitchcock did not establish a type species, Lull (1953) designated B. laqueatus as the lectotype.[4] In a recent revision of the ichnogenus, Getty (2016) recognized only two ichnospecies, B. laqueatus and B. scolependroideus; B. curvatus and B. elachistotatus were considered junior subjective synonyms of B. laqueatus, whereas B. tuberculatus was considered a nomen dubium.[5] More recently, Getty (2018) considered the ichnogenus Camurichnus as a minor morphological variant of Bifurculapes.[6] Outside of the Deerfield Basin, undoubted examples of Bifurculapes have been found only in the East Berlin Formation of the adjacent Hartford Basin (Getty 2016), the Lockatong Formation of Pennsylvania,[7] and the Moenave Formation of the Zuni sag.[8]
References
[edit]- ^ Hitchcock, Edward (1858). Ichnology of New England. A Report on the Sandstone of the Connecticut Valley, Especially its Fossil Footmarks. Boston: William White. pp. 220 p.
- ^ Getty, Patrick (2020). "Evidence that the fossil insect trackway Bifurculapes laqueatus Hitchcock, 1858 was made underwater". Acta Geologica Polonica. 70: 125–133. doi:10.24425/agp.2019.126456. Retrieved 7 April 2021.
- ^ Hitchcock, Edward (1865). Supplement to the Ichnology of New England. A Report to the Government of Massachusetts, in 1863. Boston: Wright and Potter. pp. 96 p.
- ^ Lull, Richard (1953). Triassic Life of the Connecticut Valley, Revised. Hartford: State of Connecticut. pp. 336 p.
- ^ Getty, Patrick (2016). "Bifurculapes Hitchcock 1858: a revision of the ichnogenus". Atlantic Geology. 52: 247–255. doi:10.4138/atlgeol.2016.013.
- ^ Getty, Patrick (2018). "Revision of the Early Jurassic arthropod trackways Camurichnus and Hamipes" (PDF). Boletín de la Sociedad Geológica Mexicana. 70 (2): 281–292. doi:10.18268/BSGM2018v70n2a1.
- ^ Fillmore, David; Szajna, Michael; Lucas, Spencer; Hartline, Brian; Simpson, Edward (2017). "Ichnology of a Late Triassic lake margin: The Lockatong Formation, Newark Basin, Pennsylvania". New Mexico Museum of Natural History and Science Bulletin. 76: 1–107.
- ^ Milner, A.; Harris, J.; Lockley, M.; Kirkland, J.; Matthews, N. (2009). "Bird-like anatomy, posture, and behavior revealed by an Early Jurassic theropod dinosaur resting trace". PLOS ONE. 4 (3): e4591. Bibcode:2009PLoSO...4.4591M. doi:10.1371/journal.pone.0004591. PMC 2645690. PMID 19259260.