Page 26 - maxson1928

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This lack of adjustment may be due in part to a depression of the Tertiary

invertebrate{ time scale and inJ ,part to an elevation of the corresponding

vertebrate scale. Should it become possible to ascertain accurately the

age of the· so-called lfodelo from a molluscan fauna., a partial adjustment

of the time scales of the ?a.cific Coast marine province and the Great

Basin province might be attempted since forms similar to those in each

of these provinces are coexistent at the Mint Canyon stage •

. A vertebrate occurrence to the east of Cuyama Valley, recently

investigated and partially described by Mr. C. L. Gazin, seems to be more

recent than the Mint Canyon. lt is also located in the Pacific Coast

marine province. (See Fig. l. in which it is blocked out to the northwest

of the Mint Canyon occurrence.) Stratigraphically it overlies the x,Iouelo
1
and underlies the Santa N".argari ta. formation. Providing the identification

of the Santa Clara Valley Modelo? is confirmed, there is reason to believe

that a time interval represented by a period of marien deposition

separates the 1,Unt Canyon and Cuyama vertebrate faunas.

Judging from the rather fra 111entary material which represents
6
the .darstow Camelidae, these forms are larger and possibly more advanced

than ldiolabis from the Ndnt Canyon. Protolabis montanus Douglas from the

Loup Fork beds of Colorado and Procamelus occidentalis Leidy from the

Santa Fe' beds of New Mexico a.re likewise some what larger but show some

similarity in structure. :mole.bis transmontanus (Cope) from the JJiascall

of Oregon very closely resembles the Mint Canyon species. Deducing

definite time differences from the above mentioned cameloid relationships

is not justifiable for there is a. strong possibility that the tylopod·

stock is polyphyletic.

1
Identification of formations by W. A. English

u.s.G.S. Bull. 621, 191-215, 1916