A new helminthomorph millipede, Sinosoma luopingense new genus new species, from the Triassic Luoping biota of China, has 39 body segments, metazonites with lateral swellings that bear a pair of posterolateral pits (?insertion pits for spine bases), and sternites that are unfused to the pleurotergites. This millipede shares a number of characters with nematophoran diplopods, but lacks the prominent dorsal suture characteristic of that order. Other “millipede” material from the biota is more problematic. Millipedes are a rare part of the Luoping biota, which is composed mainly of marine and near-shore organisms. Occurrences of fossil millipedes are exceedingly rare in Triassic rocks worldwide, comprising specimens from Europe, Asia, and Africa, and consisting of juliform millipedes and millipedes that are either nematophorans or forms very similar to nematophorans.

Harpactocarcinus punctulatus istriensis Bachmayer and Nosan, 1959 is elevated to species level. Analysis of the larger foraminiferans associated with specimens of H. istriensis suggests a habitat preference for off-shore, clear, shelf environments below fair-weather wave base and an age of early to middle Lutetian (Eocene). A review of the paleoenvironmental indicators for nearly all species within the genera referred to the Zanthopsidae Via, 1959 suggests that all exhibit similar habitat preferences. Description of the paleoenvironmental preference for an entire extinct decapod family has not before been possible.

A new collection of fossil decapod crustaceans from the Cretaceous Rosario Formation, the Eocene Tepetate Formation and the Oligocene El Cien Formation, Baja California Sur, Mexico, has yielded two new genera and several new species, Amydrocarcinus dantei n. gen. and sp., Levicyclus tepetate n. gen. and sp., Eriosachila bajaensis n. sp., Oregonia spinifera n. sp., Archaeopus mexicanus n. sp., and Necronectes nodosa n. sp. Additionally, new occurrences of the previously described Lophoranina bishopi, Xandaros sternbergi, Icriocarcinus xestos, and Lobonotus mexicanus as well as Dardanus cf. D. mexicanus are reported. As part of ongoing work on global evolutionary and paleobiogeographic patterns within the Decapoda, the work has prompted a review and synthesis of decapod occurrences in the tropical and subtropical Americas including the southern United States, the Caribbean, Mexico, Central America, and northern South America. As a result of the systematic review, several new combinations are reported herein which include Eriosachila bartholomaeensis (Rathbun, 1919), Lobonotus sandersi (Blow and Manning, 1996; 1998), and Matutites americanus (Rathbun, 1935). Icriocarcinus is transferred to the Goneplacidae, extending the range of that family into the Cretaceous. Most Cretaceous through Miocene tropical and subtropical American taxa appear to have originated within the area and a large number were endemic. Most of the immigrants to the central Americas appear to have evolved along North Atlantic shelves and subsequently dispersed to the Americas, probably via continental shelf routes. In addition, as demonstrated by several previous studies, decapod crustaceans appear to have evolved in numerous middle- and high- latitude areas with subsequent dispersal to lower latitudes, contrary to the long held notion that the tropics are areas of origin with subsequent dispersal to other regions. Low-latitude decapod taxa tend to remain in low-latitude areas. The Maastrichtian and the Eocene appear to have been times of elevated extinctions within the Decapoda; however, the extinction patterns for those two time intervals are very complex.

Tiny, pelagic arthropods from the Anisian Luoping Biota exposed in two quarries near Luoping, Yunnan Province, China, represent the numerically most abundant organisms in the assemblage. They form the basis for definition of two, and possibly three, species referred to the order Lophogastrida, family Eucopiidae. Yunnanocopia grandis new genus new species and Y. longicauda n. gen. new species represent the oldest occurrence of mysidaceans in the fossil record. Their anatomy allies them with the Ladinian species Schimperella acanthocercus Taylor, Schram, and Shen, 2001, from Guizhou Province, China, which previously was thought to be the oldest lophogastrid, and with extant species of Eucopiidae. Their appearance in the Anisian represents one additional element of the early faunal radiation within the Luoping Biota following the end-Permian extinction event. Presence of well-preserved oostegites, along with other morphological features, documents a conservative bauplan expressed in Eucopiidae.

Two new Raninoida crabs from the Cretaceous of Texas are described, Planocorystes robreidi new genus new species, and Texicancer new genus to accommodate Necrocarcinus renfroae. All the previously described raninoid-like decapods from the Pawpaw Formation have been reassigned according to Karasawa et al. (2014). Cretaceous raninoid-like crabs are the dominant taxa amongst the fossil decapods found in the Fort Worth, Texas, area, with hundreds of specimens collected. All of these fossils have been collected from limonitic nodules, and most of them present a good degree of preservation, with articulated pereiopods, pleons, venter and in rare occasions even the gills. The decapod fauna of the Pawpaw Formation represents a diverse population, with a large number of taxa in high abundance. One specimen of P. robreidi appears to exhibit a lethal bite mark.

A large assemblage of small specimens of Tridactylastacus sinensis Feldmann, Schweitzer, and Zhang in Feldmann et al., 2012, from the Middle Triassic (Anisian) Luoping Biota, Yunnan Province, China, permitted cladistic analysis confirming their placement within Litogastridae in the superfamily Glypheoidea. Orientation of 86 specimens closely spaced on a single slab from one bedding surface revealed a preferred orientation suggestive of mild current activity. The specimens were interpreted to have been victims of a mass kill, possibly an algal bloom, within the water column.

The xanthoid genus Xanthilites Bell, 1858 is herein restricted to contain only the type species X. bowerbanki and possibly a second species. Xanthilites sensu stricto, Pulalius, Tumidocarcinus, Paratumidocarcinus, and Baricarcinus are placed within the Tumidocarcinidae new family within the Xanthoidea. It is hypothesized that the Carpiliidae, Platyxanthidae, Tumidocarcinidae new family, Zanthopsidae, and at least some subfamilies of the Eriphiidae form a natural group and may belong to a discrete superfamily, based upon paleontological and neontological evidence. The earliest documented occurrence in the fossil record for the xanthoid Platyxanthidae is in Eocene rocks, with the referral herein of a fossil species to the family. The two related families, Eriphiidae and Platyxanthidae, are difficult to distinguish from one another in fossil specimens; diagnoses which take into account preservable characters are provided. Moreover, based upon morphological features the Eriphiidae as currently defined may comprise at least two families. Revision of Xanthilites has resulted in two new genera, Jakobsenius and Rocacarcinus, erected for Xanthilites? cretacea and X. gerthi respectively, both placed within the extinct Palaeoxanthopsidae. The common ancestor of at least some families currently referred to the Xanthoidea may lie within the Palaeoxanthopsidae, which may have embraced “pre-adapted survivor” taxa, surviving the end-Cretaceous extinction event. Goniocypoda tessieri is confirmed as a member of the Hexapodidae, extending the range of that family into the Cretaceous; however, the family is not a likely candidate for embracing the ancestral xanthoids. The illustrated specimen of Menippe frescoensis retains a barnacle epibiont, very rare in the fossil record of decapods.

New portunoid fossils from southern Argentina and from the west coast of North America permit the reevaluation of the generic and family relationships within the Portunoidea Rafinesque, 1815. It has previously been suggested that the Portunidae and the Geryonidae Colosi, 1923, are closely related families (Manning and Holthuis, 1989). The new fossils suggest that the Geryonidae may in fact be derived from a portunid progenitor, Proterocarcinus Feldmann, Casadío, Chirino-Gálvez, and Aguirre Urreta, 1995, through a process of peramorphosis in which juveniles of the geryonid species Chaceon peruvianus (d'Orbigny, 1842) resemble adults of Proterocarcinus latus (Glaessner, 1933). Examination of several genera within the portunid subfamily Polybiinae Ortmann, 1893, including Imaizumila Karasawa, 1993; Megokkos new genus; Minohellenus Karasawa, 1990; Pororaria Glaessner, 1980; Portunites Bell, 1858; and Proterocarcinus, suggests that the subfamily had an amphitropical distribution early in its history. New taxa reported here include Megokkos new genus and Portunites nodosus new species. New combinations include Chaceon peruvianus (d'Orbigny, 1842), Imaizumila araucana (Philippi, 1887), Megokkos alaskensis (Rathbun, 1926), Megokkos hexagonalis (Nagao, 1932), Megokkos macrospinus (Schweitzer, Feldmann, Tucker, and Berglund, 2000), Minohellenus triangulum (Rathbun, 1926), and Proterocarcinus latus (Glaessner, 1933).

A large collection of macrurous decapod crustaceans is recorded from the middle–late Anisian (Middle Triassic) Guanling Formation in Yunnan Province, China. A remarkable assemblage of over 20,000 vertebrate, invertebrate, and plant fossils collectively referred to as the Luoping Biota has been collected from quarries in the vicinity of the city of Luoping. Among these, arthropods including the decapods are the most common element although articulated fish and reptiles are also common. The decapods represent new taxa, including Koryncheiros luopingensis n. gen. n. sp. within Clytiopsidae, a newly elevated family within Erymoidea; Tridactylastacus sinensis n. gen. n. sp. within Glypheidae; and Yunnanopalinura schrami n. gen. n. sp. within Palinuridae. A single specimen has been referred to Palinuridae sp. Koryncheiros luopingensis exhibits a unique cheliped architecture and the second through fourth chelipeds are subchelate, an extremely rare configuration. Tridactylastacus sinensis also exhibits subchelate closures of pereiopods 2–4, but it bears a distinctive subchelate first pereiopod with an intercalated spine between the fingers on the distal margin of the propodus. Yunnanopalinura schrami represents the oldest occurrence of Palinuridae and Achelata. Collectively, these expand our knowledge of Chinese decapods significantly in that only six species of fossil decapods have been described previously from the country.

Newly discovered fossils from Eocene rocks of the Quimper Sandstone, Washington, USA, constitute the first reported occurrence of the albuneid genus Lophomastix Benedict, 1904, in the fossil record. Lophomastix and the closely related genus Blepharipoda Randall, 1839, are thought to be basal taxa within the decapod family Albuneidae Stimpson, 1858, based upon possession of primitive trichobranch gill structures. The occurrence of Lophomastix antiqua new species in Eocene deposits indicates that the genus is at least as old as the more derived genus, Albunea Weber, 1795, as would be expected for the basal taxon within the family. Based upon examination of type material, Blepharipoda brucei Rathbun, 1926, is herein removed from that genus and placed within the Paguroidea as Pagurus brucei (Rathbun, 1926) new combination.

Comprehensive analysis of the Cretaceous and Tertiary decapod crustaceans of the North Pacific Rim, focused primarily on the Brachyura, has resulted in additions to our understanding of the evolution and distribution of these animals, both in that region and globally. Hypotheses about changes in climatological and paleoceanographic conditions have not been extensively tested using decapod crustaceans, although they have been well-documented globally and for the North Pacific Ocean by sedimentological and other faunal evidence. Evidence from the occurrences of decapod crustaceans supports hypotheses obtained through these other means. Because the decapod fauna was studied independent of other faunas, it provides a means by which to compare and test patterns derived from molluscan and other faunal data. The brachyuran decapods show distinctive paleobiogeographic patterns during the Cretaceous and Tertiary, and these patterns are consistent with those documented globally in the molluscan faunas and paleoceanographic modeling. Additionally, the changes in the decapod fauna reflect patterns unique to the North Pacific Ocean. The decapod fauna is primarily comprised of a North Pacific component, a North Polar component, a component of Tethyan derivation, an amphitropical component, and a component derived from the high Southern latitudes. The Cretaceous and Tertiary decapod faunas of the North Pacific Ocean were initially dominated by taxa of North Pacific origin. Decapod diversity was highest in the Pacific Northwest of North America during the Eocene, and diversity has declined steadily since that time. Diversity in Japan was relatively low among the Decapoda until the Miocene, when diversity increased markedly due to the tropical influence of the Tethys and Indo-Pacific region. Diversity has remained high in Japan into the present time. The Cretaceous, Eocene, and Miocene were times of evolutionary bursts within the Brachyura and were separated by periods of evolutionary stasis.

Analysis of dorsal carapace characters of fossil and extant genera of the Calappidae sensu lato supports Bellwood's (1996) assignment of the group into four families based upon phylogenetic analysis, which was also supported by previous larval and morphologic studies. The Calappidae sensu stricto, Matutidae, and Hepatidae, recognized by Bell wood (1996), embrace both fossil and extant genera. The Orithyiidae is known from a single extant genus. Additionally, the Necrocarcininae Förster, known only from extinct genera, is elevated to family status. New taxa include Mursia aspina and Eriosachila rossi. Zanthopsis rathbunae Kooser and Orr, 1973, is here referred to Eriosachila orri, n. comb, and nomen novum. Emended descriptions are given for Mursia yaquinensis Rathbun, 1926, and Necrocarcinus hannae Rathbun, 1926. Biogeographic analysis indicates that each family has a distinct origination and dispersal history independent of the other families. Ecologic information for each group suggests that climatic preferences for the extant families have either remained relatively stable since the appearance of each family in the Tertiary or were broader in the past.

Members of the Etyidae and Feldmanniidae new family have unique arrangements of the spermatheca and gonopores that permit placement of each in different families and that differentiate each from all other brachyurans. Spermathecal openings are not always positioned along the sternal suture between sternites 7 and 8, suggesting that reproductive architecture within the Brachyura and what was formerly regarded as the Podotremata is considerably more diverse and disparate than previously thought. Etyidae and Feldmanniidae radiated in the early Cretaceous and survived into the Paleogene. New taxa include Steorrosia new genus, Bretonia new genus, Faksecarcinus new genus, and sixteen new combinations.

New material collected from Cretaceous and Tertiary rocks of the Pacific Northwest of North America has prompted a reevaluation of the fossil record of the Homolidae de Haan, 1839 and the Homolodromiidae Alcock, 1900. The fossil records of the homolid genera Homola Leach, 1815; Homolopsis Bell, 1863; and Hoplitocarcinus Beurlen, 1928 are restricted, and Latheticocarcinus Bishop, 1988, which is synonymous with Eohomola Collins and Rasmussen, 1992 and Metahomola Collins and Rasmussen, 1992, is reinstated as a distinctive genus. Thirteen new combinations resulted from reinstatement of Latheticocarcinus: L. adelphinus (Collins and Rasmussen, 1992), L. affinis (Jakobsen and Collins, 1997), L. atlanticus (Roberts, 1962), L. brevis (Collins, Kanie, and Karasawa, 1992), L brightoni (Wright and Collins, 1972), L. centurialis (Bishop, 1992), L. declinata (Collins, Fraaye, and Jagt, 1995), L. dispar (Roberts, 1962), L. pikeae (Bishop and Brannen, 1992), L. punctatus (Rathbun, 1917), L. schlueteri (Beurlen, 1928), L. shapiroi Bishop, 1988, L. spiniga (Jakobsen and Collins, 1997), and L. transiens (Segerberg, 1900). A new species, Latheticocarcinus ludvigseni, is described from Cretaceous rocks of British Columbia. The first fossil occurrence of the extant homolid genus Paromolopsis, P. piersoni new species, is recorded from Miocene rocks of Oregon. Paromola pritchardi Jenkins, 1977 is formally transferred to Dagnaudus Guinot and Richer de Forges (1995) as suggested by Guinot and Richer de Forges (1995). The extinct family Prosopidae von Meyer, 1860 is referred to the Homolodromioidea Alcock, 1900, following previous work. Palehomola gorrelli Rathbun, 1926 is transferred from the Homolidae to the Homolodromiidae, and the new genus Rhinodromia is erected to contain Homolopsis richardsoni Woodward, 1896, from Cretaceous rocks of British Columbia. A new terminology is suggested for describing the rostral area in homolodromiids, in an attempt to alleviate considerable confusion over that issue. The morphologic similarity of fossil and extant members in both the Homolidae and the Homolodromiidae suggest that these two brachyuran families are evolutionarily conservative, much as the lobsters are. In addition, the similar paleobiogeographic and evolutionary patterns seen in the two families suggests that either they are closely related or that brachyuran families exhibited similar evolutionary and dispersal trends early in their history.

Decapod crustacean specimens from the middle Eocene San Juan Formation in central Chiapas represent the first record of Eocene decapods in southern México. New taxa include: Dardanus mexicanus new species (Diogenidae), Lophoranina cristaspina new species, Notopus minutus new species (Raninidae); Verrucoides stenohedra new genus and new species (Xanthidae); Stoaplax nandachare new genus and new species (Goneplacidae); and Viapinnixa alvarezi new species (Pinnotheridae). Verrucoides verrucoides new genus and new combination from the Paleocene of Greenland represents a new combination. In addition, the fauna includes Callianassa sensu lato sp., Laeviranina sp., Calappilia cf. C. hondoensis Rathbun, 1930, Eriosachila sp., and indeterminate calappid and xanthoid taxa. This assemblage bears close relationship with coeval faunas in the Tethyan region of southern Europe and southern North America and with Paleocene faunas of Greenland, strengthening the evidence for previously described patterns of dispersal within the Decapoda.

Diagnoses based upon preservable carapace features are provided for the brachyuran families Carpiliidae, Palaeoxanthopsidae new family, Pseudoziidae, and Zanthopsidae, newly raised to family status. In order to make family and generic level assignments, characters of the dorsal carapace can be used successfully as proxies for soft-part morphology that is not commonly or never preserved in fossils. The identification of carpiliids and pseudoziids in the fossil record yields critical information about the time of divergence of these groups, no later than Eocene, and the relationships between those two families, the Eriphiidae, and the extinct Zanthopsidae. Because the timing of divergence of at least two xanthoid families is now known more accurately, more constrained phylogenetic studies can result. The Eocene to Recent Carpiliidae is restricted to one extant genus and five fossil genera. The Eocene to Recent Pseudoziidae contains the fossil genera Archaeozius new genus, Priabonocarcinus, and Santeezanthus as well as several extant genera; one extant genus, Euryozius, also has a fossil record. The Paleocene-Miocene Zanthopsidae embraces five extinct genera including Neoxanthopsis new genus. The new family Palaeoxanthopsidae includes four extinct genera, including Paraverrucoides new genus and Remia new genus and occurs in Maastrichtian-Eocene rocks. New combinations include Archaeozius occidentalis, Harpactoxanthopsis bittneri, Harpactoxanthopsis souverbei, Neozanthopsis bruckmanni, N. carolinensis, N. rathbunae, N. sonthofensis, N. tridentata, Ocalina straeleni, Palaeocarpilius mississippiensis, Palaeocarpilius valrovinensis, Paraverrucoides alabamensis, and Remia africana.

Paleobiogeographic patterns of decapod crustaceans from the Southern Hemisphere, based upon 441 species-level records arrayed in 154 genera, document global patterns of distribution that can be compared to those previously published on decapods from the North Pacific and Central American regions. All known records of decapods from the Southern Hemisphere spanning the Early Triassic to Pleistocene have been compiled, nearly all have been personally verified, and patterns of origin and distribution have been interpreted. Interchange between hemispheres, including amphitropical and bipolar distributions, are recognized from Jurassic to post–Miocene time. The high southern latitudes was a site of origin of several generic-level taxa during the Jurassic through Eocene and many of these taxa have been identified in subsequent times in lower latitude regions in shallow- and deepwater environments in both hemispheres. The isolation of Antarctica due to ocean currents significantly diminished the role of the high southern latitudes as an area of origin for decapods. The Tethys was an important dispersal pathway for decapods during the Cretaceous through early Miocene. Endemism was high during the Eocene, similar to the North Pacific and Central America. The magnitude of the Cretaceous/Paleogene extinction event on the Southern Hemisphere decapod fauna was not profound; most Cretaceous extinctions seem to have occurred well before the end of the Cretaceous, and 85% of the Cretaceous families are known from the Paleogene in the Southern Hemisphere taxa.

Brachyuran decapods (crabs) are rarely preserved in coastal environments and have not been documented in close association with dinosaur fossils. A crab referable to the Necrocarcinidae Förster, 1968, is here described from the Cenomanian Bahariya Formation, Bahariya Oasis, Egypt. The occurrence of a crab in a mangrove setting in association with terrestrial vertebrates is extremely unusual in the fossil record. Review of decapod occurrences from the region has resulted in placement of Portunus sp. of Roger (1946) within the Raninidae de Haan, 1839, and Lophoraninella cretacea (Dames, 1886) into the Galatheoidea Samouelle, 1819. The crabs of the Bahariya Formation were probably scavengers, feeding on vegetation and other organic material and were possibly a food source for fish and other vertebrates and invertebrates in the environment.

A new species of clawed lobster, Hoploparia albertaensis, is reported from the late Coniacian, shallow-marine Bad Heart Formation of northwestern Alberta, Canada. Hoploparia is a well-known, clawed lobster genus with a record extending from Early Cretaceous (Valanginian) to Miocene. Fifty-one species of Hoploparia are known worldwide; 13 from the North American Western Interior Seaway. None of the 12 other Interior Seaway species, of any age, closely resembles the new species. The new species strongly resembles Hoploparia gabbi Pilsbry, 1901 from the upper Santonian–lower Campanian of the U.S. Mid-Atlantic Coastal Plain.

Phyllocarids of the Waukesha Biota were systematically and taphonomically evaluated. Three Ceratiocaris species are present in the biota: C. macroura Collette and Rudkin, 2010; C. papilio Salter in Murchison, 1859; and C. pusilla Matthew, 1889. Specimens range in completeness from nearly complete, including the cephalic to caudal regions, to isolated telsons and furcae. Evidence of Salter’s position is present in only three specimens. Relatively complete specimens are interpreted to represent corpses, rather than molts; whereas specimens including only the pleon and caudal region, or caudal region, and specimens with evidence of Salter’s position likely represent exuviae. Specimens are preserved essentially as compression fossils exhibiting two types of preserved cuticle: brown inner cuticle, which tends to be impressed over the topography of bedding planes on which specimens are preserved, and blue-gray phosphatized cuticle exhibiting sub-millimeter scale relief. Cuticle phosphatization likely occurred during early diagenesis. The presence of characteristic near-shore species and C. pusilla, only known from turbidite facies, interpreted to possibly represent a marine trough, suggests that the Waukesha phyllocarid assemblage might represent a transported assemblage, rather than a biota, or that C. pusilla from the Jones Creek Formation was transported basinward in sediment gravity flows.