Dinosaur footprints often occur in Late Triassic–Early Jurassic continental sedimentary rocks. While many such tracks can readily be associated with the kinds of dinosaurs that made them, the makers of some footprints have been controversial. Large tridactyl (three-toed) footprints of the ichnogenus Eubrontes are thought by most paleontologists to have been made by theropod dinosaurs, but some workers think their makers were basal sauropodomorph (“prosauropod”) dinosaurs. The four-toed footprint Otozoum is usually interpreted as a prosauropod print, but some workers instead attribute it to an ornithischian (basal thyreophoran) dinosaur or even a pseudosuchian archosaur. These issues prompted us to do a new study of the proportions of the hindfeet of bipedal and potentially bipedal dinosaurs and other archosaurs, adding new measurements to previously available data. Foot skeletons of theropod dinosaurs differ from those of bipedal ornithischian dinosaurs in having relatively longer phalanges from the middle portions of toes, narrower phalanges, relatively shorter unguals, and a relatively shorter inner toe (digit I—but some members of both groups lose digit I altogether). Theropod feet differ from feet of prosauropods in having slightly narrower phalanges, relatively shorter unguals, and a relatively shorter digit I, but some smaller basal sauropodomorphs are harder to distinguish from theropods in these features. Feet of small to medium-sized ornithischians that retain digit I are very similar to those of most basal sauropodomorphs and also some pseudosuchians. Our results suggest that most (but perhaps not all) morphologically well-preserved Eubrontes are more likely to have been made by theropods than bipedal sauropodomorphs. It is more difficult to determine the most likely maker(s) of Otozoum.

The endostoma of eurypterids is a small ventral structure previously known from only 11 specimens and in detail from only a single species, Eurypterus tetraganophthalmus. Four previously undescribed eurypterid specimens from the Samuel J. Ciurca Jr. Collection, Yale Peabody Museum of Natural History, likely belonging to Eurypterus, and a previously documented specimen of the pterygotid Acutiramus cummingsi in the New York State Museum, are considered here to reinterpret the morphology and homologies of the endostoma. We demonstrate that the endostoma is a bilateral, flaplike appendage, with distal margins bearing anteriorly facing setae. An anterior embayment and posterior medial notch are noted. The latter represents the point where the endostoma articulates with an oval sclerite. Here we propose that, contrary to previous interpretations, the endostoma is an appendage, likely of the seventh body segment, and is probably homologous to the xiphosuran chilaria. This has direct implications for the hypotheses of homology for the metastoma, a ventral structure common to eurypterids and chasmataspids.

Crustacea type specimens from the United States Exploring Expedition of 1838–1842 present in the Yale Peabody Museum are reviewed and figured. These specimens are of historic and scientific value to the public and research communities. The five lots reviewed consist of a brachyuran crab, a caridean shrimp, and three lots of amphipods described by expedition member James D. Dana. Publishing on these accounts is an attempt to highlight these important specimens while complementing the publicly accessible collections data that is currently available.