Crab in amber reveals an early colonization of nonmarine environments during the Cretaceous Author Luque, Javier Author Xing, Lida Author Briggs, Derek E. G. Author Clark, Elizabeth G. Author Duque, Alex Author Hui, Junbo Author Mai, Huijuan Author McKellar, Ryan C. text Science Advances 2021 2021-10-20 7 1 13 journal article 10.1126/sciadv.abj5689 358054e6-cd87-43e4-b7e5-8a5a595491ca PMC8528423 34669480 5598194 Cretapsaridae Luque, fam. nov . LSID. Family group: http://zoobank.org/urn:lsid:zoobank. org:act:81705335-CAED-400E-B1EC-161B56B298AE. *Corresponding author. Email: jluque@fas.harvard.edu, luque@ualberta.ca (J.L.); xinglida@gmail.com (L.X.) Included genus: Cretapsara Luque , gen. nov. , by monotypy. Diagnosis: As for type genus and species. †These authors contributed equally to this work. ‡Present address: Florida International University, Biscayne Bay Campus, 3000 NE Remarks: Cretapsara athanata n. gen. etsp. differsfromanyknown crab family in its combination of plesiomorphic and apomorphic characters. Superficially, itsharessomeresemblancetosomemarineeubrachyuranfamiliessuch as Eogeryonidae, fromthe Upper Cretaceous of Spain [ Eogeryon elegius , Cenomanian ( 14 )] ( Fig. 5H ) and the Lower Cretaceousof Brazil [ Romualdocarcinus salesi , Albian ( 15 )], and Marocarcinidae , fromthe Upper Cretaceousof Morocco [ Marocarcinus pasinii , Cenomanian ( 16 )] ( Fig. 5E ). Cretapsara differs from Eogeryonidae and Marocarcinidae in the presenceof a bilobate rostrum and lack of orbital fissures, compared to the bifid and acute rostrum and twowell-developedorbitalfissuresdiagnostic of thesetwofamilies [ Marocarcinidae was initially interpretedas havingnoorbitalfissures due to the erroneous interpretation of the eyestalks as part of the orbit ( 16 ) but is here recognized as having two orbital fissures and scored as such in our analysis]. Fig. 1. Cretapsara athanata Luque gen. et sp. nov. , a modern-looking eubrachyuran crab in Burmese amber. ( A to D ) Holotype LYAM-9. (A) Whole amber sample with crab inclusion in ventral view. (B) Close-up of ventral carapace. (C) Whole amber sample with crab inclusion in dorsal view. (D) Close-up of dorsal carapace. White arrows in (B) and (D) indicate the detached left fifth leg orpereopod.Photos by L.X.Figure by J.L. The overall carapace outline, the broad front, long legs, and the lack of orbital fissures that characterize C. athanata ( Figs. 1 and 2 ) resemble those of some modern Grapsoidea—a group of highly terrestrial thoracotreme crabscommon in subtidal and supratidal settings worldwide. Despite this, C. athanata differs from grapsoids in important respects. In mostgrapsoids, thereisaconspicuous V-shaped notchbetweenthemerus andischium of thethirdmaxillipeds (mxp3), sothat themandiblesare visible througha large, rhomboidal gapwhen the mxp3 are closed, a featureabsent in Cretapsara ( Figs. 2 , Cand F, and 3, B, E, and G). Moreover, the podomeres of the walking legs in grapsoids, as in most thoracotreme crabs, are subtriangular to flattened in cross section, whereas those in Cretapsara are circular in cross sectionandmoresimilartothoseofotherheterotremes ( Fig.3 ,movieS1, and data file S1). Such similarities between Cretapsara and some grapsoids are likely convergent adaptations to similar ecologies.