Terminal Pleistocene Fish Remains from Homestead Cave, Utah, and Implications for Fish Biogeography in the Bonneville Basin
Eleven fish species were identified from Homestead Cave, Utah. The remains, concentrated in the lowest stratum of the deposit, were accumulated by owls between approximately 11,200 and 10,100 14C yr B.P. and likely represent fish associated with the final die-off of the Lake Bonneville fauna. Four of the species (Salvelinus confluentus, Prosopium abyssicola, Catostomus discobolus, Richardsonius balteatus) represent their first records for Lake Bonneville. The S. confluentus premaxilla is the first Quaternary specimen record for the genus in the Great Basin and suggests a southern range extension during the Pleistocene. The C. discobolus specimens represent the first fossil records for the subgenus Pantosteus in the Great Basin; their presence in Lake Bonneville documents a Pleistocene connection between two presently disjunct populations. The hyomandibulars of Prosopium gemmifer are different from Recent specimens in a pattern suggesting Holocene introgression with Prosopium spilonotus. The lack of Cottus echinatus and the presence of both Cottus bairdi and Cottus extensus may suggest the former species evolved in Utah Lake over the last approximately 10,000 yr B.P. The abundance of Catostomus ardens and the absence of Chasmistes liorus may reflect a restricted spatial distribution of the latter in Lake Bonneville.Abstract
Map of Bonneville Basin showing major paleolake levels and the location of Homestead Cave (adapted from Currey, 1990:202)
Selected diagnostic salmonid elements from Homestead Cave. (A) Lateral view of right premaxilla of cf. Salvelinus confluentus; (B) mesial view of right premaxilla of cf. S. confluentus (same specimen as A); (C) basibranchial of Oncorhynchus clarki (dorsal view); (D) left dentary of Prosopium spilonotus; (E) left dentary of Prosopium abyssicola (the ventral ramus is broken off); (F) left hyomandibular of Prosopium gemmifer (the postero-lateral ridge is on the lower, right margin of the bone), (G) left dentary of P. gemmifer. Scale: bar length = 1 mm
Comparison of the ratios of the distance between the dorsal and opercular condyles to the length of the dorsal condyle of the hyomandibular for the HC and Recent (R) Prosopium gemmifer and Prosopium spilonotus. Black triangles indicate the means; vertical bars indicate 95% confidence intervals
Selected diagnostic cyprinid, catostomid, and cottid elements from Homestead Cave. (A) Left pharyngeal tooth of Gila atraria; (B) right pharyngeal tooth of Richardsonius balteatus; (C) left dentary of Catostomus ardens; (D) right maxilla of Catostomus ardens; (E) right maxilla of Catostomus discobolus; (F) left preopercle of Cottus bairdi; (G) left preopercle of Cottus extensus. Scale: bar length = 1 mm