USNM 37570 Credneria grewiopsoides Hollick  

Notes

Hollick (1930)

Pl.53, Fig.1.

See also:

USNM 37569

 

Locality

From Hollick (1930) (p. 87-88)

"Yukon River, north bank, about 6 miles above Nahochatilton (original No. 3AH16); collected by Arthur Hollick and Sidney Paige in 1903 (lot 3252)."

 

Locality Map

 

Description

From Hollick (1930) (p. 87)

"Leaves sub orbicular, crenate-dentate above, becoming denticulate and entire below; nervation pinnate subpalmate, secondaries about six on each side of the midrib, subopposite, leaving the midrib at diverse angles of divergence, subparallel, flexuous, terminating in the dentitions, the basal pair strongest, simulating lateral primaries, with numerous branches on the under sides, of which the lower ones curve upward toward the margin and the upper ones extend to the margin and terminate in the dentitions. The larger of these specimens indicates a leaf that was apparently about 18 centimeters in length by about 20 centimeters in width across the middle."

 

Remarks

From Hollick (1930) (p. 87-88)

"In each or our specimens, unfortunately, the base is missing and only a small portion of the margin is preserved; but their identity with the genus Credneria appears to be unmistakable, although there is a resemblance to certain leaves that have been referred to
the genus Grewiopsis, such as the general type represented by the Tertiary species Grewiopsis credneriaeformis Saporta (1868) (p. 404 (116) , pl. 34 (13), fig. 7) which he lists in his table of affinities as analogous to the Cretaceous species Credneria denticulata Zenker (1833) (p. 18, pl. 2, fig. E). The latter species possesses general features that are similar to those of ours, but the dentitions are coarser and the base of the leaf is less rounded than in either of our specimens. Stiehler (1857) (p. 64, pl. 9, fig. 4) however, figures a specimen with a broader, more rounded base.

In outline our species more nearly resembles Credneria acuminata Hampe, as depicted by Stiehler (1857), p.64, pl. 10, figs. 6, 7) C. macrophylla, Heer (1869) (p. 16, pl. 4) and C. zenkeri orbicularis Richter (1905) (p. 12, pl. 2, figs. 2-3) All these species, however, have entire margins, as has also Credneria protophylloides Knowlton (1917) (p. 267, pl. 46) from the Vermejo formation of southeastern Colorado, which Knowlton compares, in respect to its general characters, with C. integerrima Zenker (1883) (p. 17, pl. 2).

Heer (1882) (p. 78, pl. 36, fig. 4) refers a leaf from the Atane beds of Greenland, without discussion, to C. integerrima, but unfortunately all of the margin except a small portion of the lower part is missing in the figure, and it is impossible to determine whether or not the upper part of the margin was entire or dentate. A comparison of this figure with ours, however, shows so striking a resemblance in all its discernible characters that there seems to be no doubt of the mutual identity of the species nor of the error in Heer 's determination of his specimen as C. integerrima.

Incidental reference may also here be made to Protophyllum nanaimo Dawson (1882 [1883]) (p. 28, pl. 8, fig. 35) represented by a fragmentary figure of a large leaf from the Cretaceous of Nanaimo, Vancouver Island, which also may belong to our species; in that event Dawson's specific name would have precedence."