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Abstract Detail



Paleobotany

Smith, MacKenzie Allan [1], Manchester, Steven R [2].

A new species of butternut (Juglans sect. Cardiocaryon) from the Miocene of Washington.

A permineralized nut of Juglans was discovered in a concretion from the mid-Miocene possibly correlative with the Astoria Formation in Grays Harbor County, Washington. The specimen was initially cut in cross-section for acetate peels. A micro CT scan was later performed which facilitated volume rendering, isosurface rendering, and virtual sections at multiple levels and orientations. Virtual transverse sections from apex to base, along with lateral views perpendicular to and parallel with the primary septum were analyzed from the CT data. The nut is ellipsoidal, about 26.3 mm long and 17.8 mm wide with a rough (bladed to scabrate) exterior surface and a smooth, basally bilobed locule. The nut shows a clear longitudinal plane of separation perpendicular to the primary septum, a central vascular strand and pair of large lacunae in the primary septum linked to very large lacunae in each half of the nutshell. These morphological characters allow for its recognition as a nut of Juglans (walnut) and more specifically as a representative of the butternuts (Juglans section Cardiocaryon), which is no longer native to the Pacific Northwest. A unique set of morphological characters distinguishes this specimen from previously described species of Juglans. Bladed to scabrate nuts of Juglans eocinerea are known from the Miocene of Banks Island, Canada but differ from this specimen in several ways including overall shape, distribution of lacunae in the primary septum and seed shape. This new species augments the smooth sculpted Juglans lacunosa from the Eocene of Washington as the example of section Cardiocaryon to be described from the Pacific Northwest. Not only does it add to the diversity of Cardiocaryon species but may shed light on the section’s evolutionary and biogeographic history. Additionally, this fossil gives more insight into the poorly known floral diversity along the Pacific Northwest’s mid-Miocene coastline.


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1 - University of Florida, Biology, 8316 SW Ashford St, Tigard, Oregon, 97224, USA
2 - University Of Florida, Florida Museum Of Natural History, PO BOX 117800, Gainesville, FL, 32611, USA

Keywords:
Juglans
butternut
Cardiocaryon
Miocene
Washington.

Presentation Type: Oral Paper
Number: 2006
Abstract ID:184
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award


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