Contributions to Zoology, 67 (4) 237-256 (1998)G. A. Bishop; R. M. Feldmann; F. Vega: The Dakoticancridae (Decapoda, Brachyura) from the Late Cretaceous of North America and Mexico

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The Dakoticancridae comprise a small, homogeneous group of podotrematous crabs that thrived in North America during the Late Cretaceous. They are sufficiently distinctive that they remain the sole family in the Dakoticancroidea. The name of the Dakoticancridae is derived from the family‘s type genus, Dakoticancer, which in turn is a name derived from the occurrence of the type species in SD, (Dakota + Cancer = Dakoticancer = Dakoticancridae).

Weller described the first dakoticancroid crab in 1905 when he described Tetracarcinus subquadratus from New Jersey figured in 1905a, figs. 4, 5, and 6, and again in 1905b (same figures but with 5 and 6 reversed) and four specimens figured in 1907 (Pl. 111, figs. 16, 17, 18, and 19). Weller did not assign the crabs to a family at the time of definition (Weller, 1905: 328); but, subsequently referred it to the family Dromiacea (sic)(Weller, 1907a: 852). He designated no holotype. These specimens were probably available to Henry B. Roberts (1962), who, as first revisor, designated the specimen illustrated by Weller 1907, fig. 17 (NJSM ♯7788) and refigured by Rathbun 1935 (pl. 10, fig. 16) as the best preserved of the "three syntypes." This specimen can be considered the lectotype.

The family was named by Rathbun in 1917. She described Dakoticancer overana Rathbun, 1917, based upon specimens sent to the National Museum by W.H. Over, of the University of South Dakota, from collections made in Pennington County, South Dakota from rocks of the Upper Cretaceous Pierre Shale. In 1935, Rathbun (1935:40) cited the type locality as being, "West side, Missouri River, a short distance below Mobridge, eastern Corson County...." In that same work, she described a new subspecies, Dakoticancer overana australis Rathbun, 1935, from the Ripley Formation, Union County, Mississippi. Rathbun (1935:26) subsequently described Dakoticancer olsoni Rathbun but Bishop (1988a:75) pointed out that this taxon did not belong in Dakoticancer.

In 1923, Rathbun described Avitelmessus grapsoideus from a large male specimen (USNM ♯31895) collected from the Peedee Formation by L.W. Stephenson (Coll. ♯3452) "Near Hudlers Landing, Cape Fear River, 30 1/2 miles above Wilmington...." Rathbun assigned this crab to the Family Atelecyclidae (1923:403). She subsequently (1926:190-191, Pls. 69-70) described and illustrated several additional specimens from western Tennessee. Kesling and Reimann (1957) further enhanced our knowledge of Avitelmessus grapsoideus by their description and illustration of a magnificently prepared specimen from the Coon Creek Formation, Coon Creek, Tennessee (Univ. Mich. Museum Paleont. ♯33406) that preserves the dorsal, anterior, and lateral aspects of the carapace and proximal pereiopods, including both chelipedes. This specimen was described in great detail and illustrated by nine figures. A color pattern was discerned and described. The assignment to the Atelecyclidae was maintained by their allusion to Rathbun‘s assignment and by a comparison to the atelecyclid Bellia picta Edwards from the coast of Peru. It must be noted that, subsequently Bellia has been assigned to the Bellidae and is no longer referred to the Atelecyclidae. Avitelmessus was subsequently assigned to the Dakoticancridae (Glaessner, 1960). The genus remains a significant one in that it may be ancestral to another family. Glaessner (1969:440) said, "A derivative of the Cancridea from a form like the Upper Cretaceous Avitelmessus (Dakoticancridae, originally placed in Atelecyclidae) seems possible."

To this list of taxa, Bishop added two additional genera, Lathelicocarcinus Bishop, 1988b, and Seorsus Bishop, 1988a. Both were based upon specimens collected from lower Maastrichtian deposits in Mississippi. The former genus is probably referrable to a different family and the latter is known only from the type material. Subsequent work on the family has resulted in the elevation of Dakoticancer overana australis to species rank (Bishop, 1983b), as well as enhancement of our understanding of the biology and biogeography of the included species.

As presently understood, the group is small and of limited geologic and geographic scope, although specimens are abundant in fossil laggerstatten in North America. Nonetheless, Glaessner (1980) suggested that the family might figure prominently in the evolutionary history of the decapod crustaceans and applied the taxonomy of Guinot (1977, 1978) that distinguished three major groups of crabs, the Podotremata, Heterotremata, and Thoractotremata, into which were integrated the traditional families of brachyurans. Glaessner‘s interpretation of the evolution of the Brachyura documented three major times of adaptive radiations; Middle and Upper Jurassic, Mid-Cretaceous, and the Late Cretaceous-Early Paleogene. Implied, but not cited in the text description is a fourth radiation in the Eocene. No mention is made of the Dakoticancridae on Glaessner‘s chart, nor in its description, however, Glaessner (1980:188) did cite it earlier in his text, "A similarity of the carapace with that of Avitelmessus Rathbun does not apply to its [Pororaria eocenica Glaessner 1980] median portion which shows a corystoid pattern. Avitelmessus is very close to Dakoticancer. Pororaria eocenica has since been referred to the Portunidae (Feldmann and Maxwell, 1990). As Guinot (1978) remarked, "these genera should not be assigned to the Dromiacea." This is an interesting situation, especially since Glaessner called attention to the Dakoticancridae as an unanswered problem (1960:47) "...(3) the Upper Cretaceous Dakoticancridae including Avitelmessus grapsoideus Rathbun and their relation to a group of large-eyed American Crabs comprising Archaeopus antennatus Rathbun, "Plagiolophus" vancouverensis (Woodward), Carcineretes and Ophthalmoplax. Within this incompletely known group may lie the key to the genetic relationships of the Dorippidae and other Oxyrhyncha, the Ocypodidae, and possibly the Portunidae." If, as Glaessner suggests, they are not assignable to the Dromiacea, where do the dakoticancroids belong? and, What was their origin? Guinot (1993) considered the Dakoticancridae to be the sole family within the Dakoticancroidea; This superfamily she considered to be separate and apart from both the Dromiacea and Archaeobrachyura.