37-5 Dinosaur Integument Traces from the Brushy Basin Member of the Morrison, Curecanti National Recreation Area, Western Colorado

Session: Geoscience Research Poster Showcase by 2YC and 4YCU Undergraduate Students

Poster Booth No.: 128

Presenting Author:

Fenn Garnett

Authors:

Garnett, Fenn¹, Heppner, Kade², Darrell, Teyha ³, Glen, Kyleigh⁴, King, Michael Ryan⁵, Hunt-Foster, ReBecca K.⁶

(1) Natural & Environmental Sciences, Western Colorado University, Gunnison, CO, USA, (2) Natural & Environmental Sciences, Western Colorado University, Gunnison, CO, USA, (3) Natural & Environmental Sciences, Western Colorado University, Gunnison, CO, USA, (4) Natural & Environmental Sciences, Western Colorado University, Gunnison, CO, USA, (5) Natural & Environmental Sciences, Western Colorado University, Gunnison, CO, USA, (6) National Park Service, Dinosaur National Monument, Vernal, UT, USA,

Abstract:

Skin impression trace fossils provide rare evidence of dinosaur external anatomy, but isolated specimens are difficult to identify without associated skeletal material. This study evaluates two skin-impression molds, BB1 and BB2, from the Brushy Basin Member of the Upper Jurassic Morrison Formation in Curecanti National Recreation Area to determine whether their scale morphology is consistent with sauropod integument. Maximum scale length, width, and relief depth were measured with calipers, and the shape of polygons were noted on both specimens. These measurements were compared with a cast of Barosaurus lentus forelimb skin from Dinosaur National Monument and with published sauropod skin-impression data. BB1 contains large, deeply relieved polygonal scales averaging 38.5 mm long, 32.5 mm wide, and 5.7 mm deep. BB2 preserves smaller polygonal scales averaging 22.8 mm long, 17.0 mm wide, and 3.1 mm deep. The Barosaurus cast has smaller, more tightly packed, rounded scales averaging 13.0 mm long and 1.6 mm deep. BB2 falls within published sauropod scale-size ranges and exhibits the characteristic non-overlapping, honeycomb arrangement of sauropod skin. Its mixture of scale sizes and packing densities may represent a transitional region between a flexible limb and a more rigid body surface. BB1 exceeds most published sauropod scale dimensions, but its morphology resembles large hexagonal impressions previously attributed to sauropods from the Morrison Formation. Although a non-sauropod origin cannot be excluded, the polygonal arrangement and regional comparisons support a sauropod affinity for both specimens.

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