Avitelmessus grapsoideus
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Brachyura
Family: Dakoticancridae
Genus: Avitelmessus
Rathbun, 1923[1]
Species: A. grapsoideus
Binomial name
Avitelmessus grapsoideus
Rathbun, 1923

Avitelmessus grapsoideus is an extinct species of dakoticancrid crustacean that lived during the Late Cretaceous. It is the only species in the genus Avitelmessus and is known from finds in the southeastern United States.[2]

Taxonomical history[]

Avitelmessus was described in 1923 by Mary J. Rathbun, who assigned it to the family Atelecyclidae.[1][3] Martin Glaessner later reassigned it to the family Dakoticancridae in 1960.[3][4]


The exoskeleton of Avitelmessus was about 2.25 inches (5.7 cm) in length and was nearly ovular in shape, with a "rounded outline".[2] The upper surface was marked by "broad, shallow grooves" which formed two attached diamond-like shapes, with the larger one closer to the front.[2] "Subsidiary" grooves came in contact with both sides of the larger diamond.[2] The "fairly blunt" anterior edge of the carapace possessed a small, central rostrum, with orbits on either side.[2] The front legs were modified to become chelipeds, with pincers formed by an upper finger, which was movable, and a lower finger, which was stationary (an extension of the previous leg segment). All limbs were covered by "fine granules".[2] At least one specimen with "color markings" (considered rare among fossil crabs) has been discovered.[1] The colors are described as "a medium background, dark spots and blotches, and light lines".[1]

Fossil sites[]

Avitelmessus was originally described by Rathbun based on the holotype from the Peedee Formation of North Carolina, as well as specimens from the Ripley Formation of Mississippi. Later, she would also describe specimens from western Tennessee.[1] Avitelmessus is also present on the Atlantic coastal plain and in the Mississippi Embayment. The "near restriction" of Avitelmessus to the Mississippi embayment (and that of other Dakoticancridae members to other specific areas) suggest "provincialism" among the family.[5]


Smaller than a Microraptor!

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  1. 1.0 1.1 1.2 1.3 1.4 Kesling, Robert V. (January 18, 1957). "An Upper Cretaceous crab, Avitelmessus grapsoideus Rathbun". Contributions from the Museum of Paleontology 14 (1): 1–15. 
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Palmer, Douglas (2009). "Cretaceous". In Burnie, David. Prehistoric Life: the Definitive Visual History of Life on Earth (first American ed.). New York, NY: DK Publishing. p. 303. ISBN 978-0-7566-5573-0. 
  3. 3.0 3.1 Bishop, G. A. (1998). "The Dakoticancridae (Decapoda, Brachyura) from the Late Cretaceous of North America and Mexico". Contributions to Zoology 67 (4): 237–256. 
  4. Bishop, Gale A. (1988). "A new crab, Seorsus wadei, from the Late Cretaceous Coon Creek Formation, Union Country, Mississippi". Proceedings of the Biological Society of Washington 101 (1–4): 72–78. 
  5. Bishop, Gale A. (1986). "Occurrence, preservation, and biogeography of the Cretaceous crabs of North America". In Gore, Robert H.. Crustacean Biogeography. Crustacean Issues. 4. A. A. Balkema. p. 130. ISBN 978-90-6191-593-5. https://books.google.com/books?id=K-TBhXILCkkC&pg=PA130&hl=en&sa=X&ei=V2GHT8CvJMf40gG0v9D0Bw&ved=0CDMQ6AEwAA#v=onepage&q&f=true.