Serbet, Rudolph , Manchester, Steven R. , Aulenback, Kevin , Braman, Dennis .
Nyssaceae among the Dinosaurs: Anatomically preserved fruits from the Upper Cretaceous Horseshoe Canyon Formation, Drumheller, Alberta, Canada.
Silicified fruits from Late Campanian carbonaceous ironstones of the Horseshoe Canyon Formation near Drumheller, Alberta, Canada, include specimens clearly referable to the Nyssaceae. These fruits occur along with other plant remains in the same horizon as theropod and hadrosaur remains. Removal of the surrounding sediment with hydrochloric acid reveals the external sculpture of the fruits, while serial sectioning reveals the internal anatomy. Two nyssaceous fruit types are recognized, both having fusiform, multilocular endocarps composed of fibers, lacking an axial vascular bundle, and possessing a dorsal germination valve over each locule. The first morphotype is very similar to the extant Asian genus, Davidia: Its endocarp is fusiform with numerous meridional ridges and grooves, 10 to 17 mm long and 5 to 8 mm in diameter. The number of locules varies from five to six; however, some of the locules remain small, while others (usually one, but sometimes two or three) develop to contain a mature seed. In the features preserved, these fruits conform to the genus Davidia, differing only by their smaller size. The second morphotype is distinguished by smoother sculpture, smaller size and tricarpellate morphology. The endocarps are 8 to 13 mm long and ca 3 mm in diameter. These trilocular fruits are typically triangular in transverse section. The nature of the infructescence on which these fruits were borne is still not known. If they were borne in heads subtended by bracts, the species could be confidently placed in Amersinia, an extinct nyssaceous genus that was common in the Paleocene of North America and Asia. Preliminary work on nearby beds indicates the presence of leaves similar to Davidia and Beringiaphyllum. The abundance of these fruits and leaves indicates that Nyssaceae were aready well established in the Late Cretaceous--at least six million years earlier than the previously documented Paleocene records.
1 - University of Florida, Department of Natural History, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
2 - University of Kansas, Natural History Museum and Biodiversity Research Center, 1345 Jayhawk Blvd., Lawrence, Kansas, 66045-7534, USA
3 - Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, Alberta, T0J 0Y0, Canada
Presentation Type: Paper
Location: Maybird (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 2:15 PM