Vertebrate remains have been found on gravel bars of the Red River in southwest Arkansas, northeast Louisiana, and east Texas. The majority of these specimens were recovered by amateur archaeologists and Dr. Frank Schambach of the Arkansas Archaeology Survey. Extinct species of bison (Bison sp.), mastodon (Mammut americanum), pampathere (Holmesina septentrionalis), llama (Palaeolama mirifica), tortoises (Geochelone sp.), and (Terrapene sp.) indicate a Pleistocene component in the region's alluvium. The giant tortoise, pampathere, and llama represent first known occurrences of these species for the state of Arkansas. Search times between finds were recorded for seven localities. The richest gravel bar averaged one man-minute per find. The least productive bar averaged 82.5 man-minutes per find. The average collection rate for all bars was one find per 19.5 man-minutes.
Sanders, Terry A.
"Pleistocene and Halocene Remains from the Red River, Southwest Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 48
, Article 34.
Available at: http://scholarworks.uark.edu/jaas/vol48/iss1/34