Beecher's Trilobite Bed

Beecher's Trilobite Bed
Stratigraphic range: Late Ordovician (Caradoc, c.445 Ma)
Type Geological formation
Unit of Frankfort Formation
Area Small quarry only
Thickness 3-4 cm
Lithology
Primary Shale
Location
Coordinates 43°15.2′N 75°24.5′W / 43.2533°N 75.4083°W / 43.2533; -75.4083
Region Oneida Co., New York.
Country USA
Extent Very limited
Type section
Named for Charles Emerson Beecher

Beecher's Trilobite Bed is a Konservat-Lagerstätte of Late Ordovician (Caradoc) age located within the Frankfort Shale in Cleveland's Glen, Oneida County, New York, USA.[1][2] Only 3-4 centimeters thick, Beecher's Trilobite Bed has yielded numerous exceptionally preserved trilobites with the ventral anatomy and soft tissue intact, the soft tissue preserved by pyrite replacement.[2][3] Pyritisation allows the use of X-rays to study fine detail of preserved soft body parts still within the host rock.[4][5] Pyrite replacement of soft tissue is unusual in the fossil record;[6] the only Lagerstätten thought to show such preservation were Beecher's Trilobite Bed, the Devonian Hunsrück Slates of Germany, and the Jurassic beds of La Voulte-sur-Rhône in France,[7] although new locations are coming to light in New York state.[8]

History of research

Originally discovered in 1892 by William S. Valiant, the site was thoroughly excavated from 1893 to 1895 by Charles Emerson Beecher (after whom the location is named) of Yale University, after which time the location was thought to be exhausted of fossils and excavations ceased.[9] Beecher published three papers describing a trilobite larval form,[10] trilobite limbs[11] and trilobite ventral anatomy[12] from material collected from the site he established. Beecher died unexpectedly in 1904; much material, as well as details of the location, was lost.[13] Research was subsequently limited to study of material collected during the original excavations that had been distributed to various institutions.[13][14][15]

Amateur fossil collectors Tom E. Whiteley (also responsible for rediscovering the Walcott-Rust quarry) and Dan Cooper rediscovered the location in 1984[16] and from 1985 academic excavations and studies (re)-commenced.[17] At least 4 other fossil bearing horizons exhibiting similar preservation have subsequently been found at the original site.[17] The small quarry at the site is currently closed to public access,[18] being on private land[17] and administered by Yale Peabody Museum as part of ongoing research projects.[19]

Sedimentology, environment of deposition & preservation

The original Beecher's Trilobite Bed is found within a thick succession of fine grained turbidite beds, the fossiliferous bed is about 40 mm thick laying on a scoured mudstone surface with remnants of burrows.[14] Well preserved fossil remains are found 7–10 mm above the base parallel to the bedding plane, strongly aligned by the current, with as many facing up as down.[6][12][14] Chemically, the bed contains high iron coupled with low organic carbon and low organic sulphur.[6]

Fauna

The trilobite Triarthrus eatoni comprises 85% of the organisms sampled at the locality, other taxa include graptolites, branching algae, brachiopods and problematica.[20] The trilobites Cryptolithus bellulus (Ulrich), Cornuproetus beecheri (Ruedeman), Primaspis crosotus (Locke) are also recorded.[2]

See also

References

  1. ↑ Martha Buck's senior thesis on the Beecher's Trilobite Bed
  2. 1 2 3 Photos (and more) of trilobites from Beecher's Trilobite Bed from Yale Peabody Museum
  3. ↑ Butterfield, Nicholas J. (2003). "Exceptional Fossil Preservation and the Cambrian Explosion". Integrative and Comparative Biology 43 (1): 166–177. doi:10.1093/icb/43.1.166. PMID 21680421.
  4. ↑ Simon Conway Morris (1991). "In search of the lost fossil record" (PDF). Endeavour, New Series 15 (4): 158–164. doi:10.1016/0160-9327(91)90121-Q.
  5. ↑ X-ray images and 3D GIFs of preserved trilobite appendages by Amherst College
  6. 1 2 3 Derek E.G. Briggs; Simon H. Bottrell; Robert Raiswell (1991). "Pyritization of soft-bodied fossils: Beecher's Trilobite Bed, Upper Ordovician, New York State". Geology 19 (12): 1221–1224. Bibcode:1991Geo....19.1221B. doi:10.1130/0091-7613(1991)019<1221:POSBFB>2.3.CO;2.
  7. ↑ Paul A. Selden; John R. Nudds (2005). Evolution of Fossil Ecosystems (PDF). University of Chicago Press, IL. p. 192. ISBN 978-0-226-74641-8. see page 41
  8. ↑ Farrell, Úna C.; Briggs, Derek E. G. (2008). "Pyritized olenid trilobite faunas of upstate NY: palaeoecology and taphonomy (abstract)" (pdf). Palaeontological Association Programme with Abstracts 52: 23.
  9. ↑ Etter, Walter (2002). "Beecher's Trilobite Bed: Ordovician Pyritization for the Other Half of the Trilobite". In David J. Bottjer, Walter Etter, James W. Hagadorn & Carol M. Tang (eds.). Exceptional Fossil Preservation: A Unique View on the Evolution of Marine Life. Columbia University Press, NY. pp. 131–142.
  10. ↑ Beecher, C.E. (1893a). "A larval form of Triarthrus". American Journal of Science 46: 361–362.
  11. ↑ Beecher, C.E. (1893b). "On the thoracic legs of Triarthrus". American Journal of Science 46: 467–470.
  12. 1 2 Beecher, C.E. (1902). "The ventral integument of trilobites". American Journal of Science. Series 4 13: 165–173.
  13. 1 2 Raymond, Percy E. (1920). "The Appendages, Anatomy and Relationships of Trilobites". The Memoirs of the Connecticut Academy of Arts and Sciences 7.
  14. 1 2 3 Cisne, John L. (1973). "Beecher’s Trilobite Bed revisited; ecology of an Ordovician deepwater fauna". Postilla 160: 1–25.
  15. ↑ Cisne, John L. (1981). "Triarthrus Eatoni (Trilobita): Anatomy of its exoskeletal, skeletomuscular, and digestive systems". Palaeontographica Americana 9: 1–142.
  16. ↑ Brett, Carlton E.; Whiteley, Thomas E. (2005). "Presentation of the Harrell L. Strimple Award of the Paleontological Society to Thomas E. Whitely/response by Thomeas E. Whitely". Journal of Paleontology 79 (4): 831–4. doi:10.1666/0022-3360(2005)079[0831:POTHLS]2.0.CO;2.
  17. 1 2 3 Farrell, Una (2008). "Revisiting Beecher's Trilobite Beds" (PDF). Yale Environmental News 13 (1): 9.
  18. ↑ Forum talk regarding quarry access.
  19. ↑ Yale Peabody (Briggs Laboratory) research projects.
  20. ↑ James W. Hagadorn; Martha M. Buck (2004). "Digital Paleobiology and Taphonomy of an Ordovician lagerstätte: Beecher's Trilobite Bed". Geological Society of America Abstracts with Programs 36 (5): 383.
This article is issued from Wikipedia - version of the Sunday, January 10, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.