COMPARISONS OF FOSSIL BIOTAS OF THE LATE CARBONIFEROUS GARNETT AND HAMILTON QUARRY LOCALITIES, EASTERN KANSAS

Garnett and Hamilton Quarry fossil localities of eastern Kansas represent one of the most comprehensive windows to nearshore terrestrial paleoecosystems of the Late Carboniferous, approximately 299 to 306 million years ago. Both localities contain exceptionally preserved plants, invertebrates, and vertebrates. Although Garnett and Hamilton have been compared globally to other Carboniferous localities, rarely are they compared to each other. A goal of this project was to make direct comparisons of the localities based on the fossil taxa to gain a better understanding of how their biotas are are similar and different. Representatives of the invertebrates bivalves, brachiopods, arachnids, cockroaches, and dragonflies were found at both Garnett and Hamilton. However, genera of these groups at the two localities were completely different with the exception of Neospirifer and Myalinella. Furthermore, only Hamilton has gastropods, shrimps and millipedes. Among vertebrates, fish are the most diverse at Hamilton. Only coelacanths and xenacanthid sharks were found at both localities. Batrachomorph ampbibians are found at both, whereas reptilomorph amphibians are only found at Garnett. The earliest and most primitive diapsid reptile is from Garnett, and Hamilton has a closely related species. In contrast, Hamilton has the most basal euplelycosaur synapsid, whereas Garnett has more derived species, even though the latter locality is older. At Garnett, seed ferns have the highest plant diversity and conifers the lowest, whereas at Hamilton it is the reverse. Overall, Garnett has a more terrestrial biota, whereas Hamilton Quarry has a more freshwater aquatic biota.