Emeraldella

Emeraldella is a genus of arthropod known from the Middle Cambrian of North America. The type species E. brocki was described in 1912 from the Burgess Shale.[1] 21 specimens of Emeraldella are known from the Greater Phyllopod bed, where they comprise < 0.1% of the community.[2] A re-study on the species was done in 2012.[3] A second species E. brutoni is known from the Wheeler Shale, which was described in 2011.[4] An additional specimen of E. brutoni was described in 2019, which revealed more of the anatomy.[5] It has been placed as a basal member of the clade Vicissicaudata within Artiopoda, a group of arthropods containing trilobites and their relatives.[5]

Emeraldella
Temporal range:
Emeraldella brocki
Emeraldella brutoni
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
(unranked): †Artiopoda
(unranked): †Vicissicaudata
Genus: †Emeraldella
Walcott, 1912
Type species
Emeraldella brocki
Walcott, 1912
Other species

Emeraldella brutoni Stein, Church & Robison, 2011

Reconstruction of Emeraldella brutoni

Description

Caudal flaps are present on the terminal tergite, alongside an elongated spine.[3]

Emeraldella brocki

E. brocki is at least 60 mm in length, it possesses 12 tergites in the trunk section, with an extended telson. The attenula are long and can reach the length of the body, and are composed of more than 80 segments. Ocular structures appear to be absent in this species.[3]

Emeraldella brutoni

E. brutoni is up to 50 mm in length, possesses 10 trunk tergites and a clear ocellii. Unlike E. brocki, its antennae are not preserved well enough to estimate the true length.[5]

References
  1. "II.—Cambrian Geology and Palæontology. No. 6: Middle Cambrian Beanchiopoda, Malacostraca, Trilobita, and Merostomata. By C. D. Walcott. Smithsonian Miscellaneous Collections, vol. lvii, No. 6 (publication 2051), 1912". Geological Magazine. 9 (8): 376–377. August 1912. Bibcode:1912GeoM....9..376.. doi:10.1017/s0016756800115006. ISSN 0016-7568.
  2. Caron, Jean-Bernard; Jackson, Donald A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS. 21 (5): 451–65. Bibcode:2006Palai..21..451C. doi:10.2110/palo.2003.P05-070R. JSTOR 20173022. S2CID 53646959.
  3. Stein, Martin; Selden, Paul A. (June 2012). "A restudy of the Burgess Shale (Cambrian) arthropod Emeraldella brocki and reassessment of its affinities". Journal of Systematic Palaeontology. 10 (2): 361–383. doi:10.1080/14772019.2011.566634. ISSN 1477-2019. S2CID 55018927.
  4. "A new Cambrian arthropod, Emeraldella brutoni, from Utah". Paleontological Contributions. 2011-09-29. doi:10.17161/PC.1808.8086. hdl:1808/8086. ISSN 1946-0279.
  5. Lerosey-Aubril, Rudy; Ortega-Hernández, Javier (2019-10-31). "Appendicular anatomy of the artiopod Emeraldella brutoni from the middle Cambrian (Drumian) of western Utah". PeerJ. 7: e7945. doi:10.7717/peerj.7945. ISSN 2167-8359. PMC 6825744. PMID 31687274.
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