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Show 218 Forester, verbal communication, 1994). As P. compressa, which is compressed through its poles, nears the K-T boundary, its polar diameter typically increases. 4.4.3. Ostracods The ostracods of North Horn Mountain indicators rather than diverse and as occur more biostratigraphic indices, commonly section. Several ostracod taxa which are Pseudocypridina (Bisulcocypridea) (basal The 50 but environmental found that in the K-T interval, the most occur sp. cf. P. they are more parts of the common of longa (Figure 4.9) and Cypridea Bisulcocypridea of this ostracod genus we as in the K-T interval than in other occurs of the North Horn Formation of Price m) species bisulcata. studied were change in the Maastrichtian Canyon (Fouch across the K- T et boundary portion al., 1987). from the interval between the base of the coal sequence and the contact between the upper and lower coal sequence Mountain). Pseudocypridina disappears, written to 208 Brouwers and DeDeckker Bisulcocypridea elsewhere it (163 or is (1996) above base at North Horn describe similar longa is common only rarely after the at North Horn of the coal sequence. It K-T boundary occurs in in limestone at 184 m in China (F. M. Swain, to the distribution of common in the lowest anomalously high numbers relative to its Mountain, where it is numbers elsewhere in the sequence species in in the Maastrichtian levels, and communication, 1994). This pattern is similar Pseudocypridina changes in the Western Interior. sp. ct. P. seen m or part relative to numbers of other ostracod above the base of the formation at North Horn |
