The Pleistocene of North America / and its vertebrated animals from the states east of the Mississippi River and from the Canadian provinces east of longitude 95°

by Oliver Perry Hay

MICHIGAN.

(Map [28].)

1. Berrien County.—In the American Museum of Natural History, New York, is a nearly complete skull with the left ramus of the lower jaw, purchased from Mr. George A. Baker. The exact place in the county where it was found is unknown, and the writer has been unable to get into communication with Mr. Baker.

As to the time in the Pleistocene when this individual lived, we may be sure that it was after the Wisconsin glacial ice-sheet had abandoned this county. How long after this retirement it is impossible to say. It is to be noted that both mastodons and mammoths have been found in this county, in what appear to be deposits of the same age.

2. Adrian, Lenawee County.—In the U. S. National Museum is a skull of Castoroides (Cat. No. 197), of which the lower jaw is missing. This was received June 10, 1880, from Professor J. Kost, then of Adrian College, Michigan. In his letter Professor Kost wrote as follows:

“Found in fresh-water marsh, 4 feet under, in Adrian, Lenawee Co., Michigan. In same place as the Decker mastodon, now in Adrian College; also of lower jaw of smaller mastodon (sent in this consignment), with various bones of elk, deer, etc.”

The mastodon jaw referred to is in the U. S. National Museum (No. 188). The present writer has not been able to learn exactly where all these bones were obtained. It would be interesting to know whether all–mastodons, giant beaver, elk, and deer–were found in the same excavation. It is probable that they were at least in nearly the same spot. For remark on the age of the deposits at Adrian see page [81].

3. Ann Arbor, Washtenaw County.—In the collection of the Department of Geology in the University of Michigan is a skull which lacks the lower jaw and is otherwise slightly injured. A report of this specimen was made in 1914 by Mr. N. A. Wood (Science, n. s., vol. XXXIX, p. 759). This was found several years ago in a peat-bog on the farm of Professor J. B. Steere, 3 miles south of Ann Arbor, at a depth said to have been about 3 feet. Beneath the peat and muck is a gravelly marl. According to the Ann Arbor Folio (No. 155, U. S. Geol. Surv.), there is, running south from the city, a strip of low ground designated as occupied by peat and muck. This borders on the east a part of the Fort Wayne moraine, and must have provided an ideal spot for colonies of these great beavers. Naturally these specimens must be credited to the Late Wisconsin stage.

4. Attica, Lapeer County.—In the collection of Alma College, Alma, Michigan, is a fragment of an upper incisor, found at a depth of 7 feet, in digging the tail-race of a mill in Attica. The statement was made that at the same place there were often found what appeared to have been beaver dams made of wood. This wood crumbled on coming to the air. In cases like this there is a fine opportunity to determine whether or not the wood had been gnawed by the broad incisors of Castoroides or by the narrower ones of the existing beaver. The wood might easily be prevented from crumbling by replacing the water with a solution of gum arabic or even of glue.

Attica is situated some distance outside of the beaches of old Lake Maumee, and on low ground between morainic tracts left by the Saginaw lobe in its retreat. These gigantic beavers must, therefore, have lived near the close of the Pleistocene.

5. Owosso, Shiawassee County.—In the collection of the University of Michigan (No. 3109) is the greater part of a lower jaw of a giant beaver, found somewhere near Owosso, in a swamp deposit. An account of this specimen was given in 1914 by Mr. N. A. Wood (Science, n. s., vol. XXXIX, p. 758). It was received from Mr. A. G. Williams in 1892. According to Leverett and Taylor’s glacial map of Michigan, Owosso lies a few miles outside of the beach of old Lake Saginaw. This is supposed to have come into existence about the close of the period of Lake Maumee. The earliest time when this beaver might have existed, leaving out the question of the climate, would coincide closely with the time when the one found at Attica might have lived. It is most probable that both lived at a time when the glacier front was farther away.