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Journal of Vertebrate Paleontology - New Early Miocene Camelid From The Las Cascadas Formation, Panama Canal, Central America
Congreso
Authorship:
ALDO F. RINCON ; JONATHAN I. BLOCH ; BRUCE J. MACFADDEN ; SANDRA SUAREZ ; CARLOS JARAMILLODate:
2010Publishing House and Editing Place:
SOC VERTEBRATE PALEONTOLOGYISSN:
0272-4634Summary *
Expansion of the Panama Canal that began in 2008 has resulted in renewed focus on geo- logical and paleontological research. New exposures of outcrops have resulted in recovery of many additional vertebrate fossils from the previously known early Miocene Cucaracha Formation (Centenario Fauna). Here we report the first known mammals from the underly- ing late Oligocene/early Miocene Las Cascadas Formation, a volcanoclastic and tuffaceous sequence outcropping in the southern part of the Panama Canal. The faunal assemblage includes the oldest records of carnivores, rodents, peccaries, equids, anthracotheres, protoc- eratids, and camelids from the Panama Canal. The new camelids, represented by two partial dentaries and isolated lower teeth, can be attributed to Floridatragulinae based on the follow- ing characteristics: 1) a complete lower dental formula, 2) brachydont lower molars, 3) an unusual elongated jaw with 2 caniniform teeth (C/1-P/1) well separated by a diastema; 4) a long and narrow mandibular symphysis; 5) reduced lower premolars; 6) small intercolum- nar pillars present in the molars; and 7) an M/3 hypoconulid divided by lingual and labial selenes. This new Central American floridatraguline lacks the presumably more derived P/2-P/3 diastema present in Hemingfordian-Barstovian North American Floridatragulus (F. dolinchanthereus, F. hesperus, F. nanus and F. texanus) suggesting a primitive morphologi- cal state similar to the potentially younger floridatraguline Aguascalentia wilsoni from the Hemingfordian of Mexico and possibly Aguascalentia sp. from the Arikareean of the Texas Big Bend area. Preliminary geochronological and stratigraphical data indicate that the Las Cascadas local fauna may constitute a distinctive Arikareean faunal province characterized by the arrival of early Miocene northern immigrants into a small continental basin clearly connected with North American continental terrains. The inferred appearances of Aguas- calentia in the Hemingfordian of Mexico and the late Arikareean of Texas and Panama are consistent with the idea that ungulates appearing in the early Miocene of North America may have had their origins in Central America. Information provided by the agent in SIGEVAKey Words
CASCADASCAMELIDCANALPANAMA