Preliminary Survey of a Paleocene Faunule From the Angels Peak Area, New Mexico

Part 1

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Preliminary Survey of a Paleocene Faunule from the Angels Peak Area, New Mexico

ROBERT W. WILSON

University of Kansas Publications Museum of Natural History

Volume 5, No. 1, pp. 1-11, 1 figure in text February 24, 1951

University of Kansas LAWRENCE 1951

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Edward H. Taylor, Robert W. Wilson

Volume 5, No. 1, pp. 1-11, 1 figure in text

February 24, 1951

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1951

23-4458

Preliminary Survey of a Paleocene Faunule from the Angels Peak Area, New Mexico

ROBERT W. WILSON

INTRODUCTION

Angels Peak stands on the eastern rim of a large area of badlands carved by a tributary of the San Juan River from Paleocene strata of the Nacimiento formation, and presumably also from Wasatchian strata of the San José (Simpson, 1948). This area of badlands lies some twelve miles south of Bloomfield, New Mexico in the Kutz Canyon drainage. Angels Peak (Angel Peak of Granger, 1917) and Kutz Canyon (Coots Cañon of Granger, and of Matthew, 1937) are names that have been applied to the location (figure 1).

E. D. Cope's collector, David Baldwin, possibly worked in this area in the Eighties. The first published record, however, of mammalian fossils from the Angels Peak badlands was made by Walter Granger in 1917 as a result of his field work in the preceding summer. Granger obtained specimens, usually poorly preserved, but occasionally rather abundant locally, from various levels up to within 150 feet of the western rim of the badlands basin. This collection was obviously of Torrejonian or middle Paleocene age. In the 1917 report, Granger gave as a faunal list the following species:

Tetraclaenodon Mioclaenus turgidus Periptychus rhabdodon Anisonchus sectorius Protogonodon sp. nov. Tricentes Deltatherium Psittacotherium

To this list should be added Triisodon antiquus, a specimen of which is stated by Matthew to come from Kutz Canyon in his monograph (1937:80) on the Paleocene faunas of the San Juan Basin.

In the summer of 1948, a field party from the University of Kansas was fortunate in finding a local concentration of rather well preserved material at the western edge of the badlands at Angels Peak. Because it probably will be some time before a full account of this faunule can be prepared, it is thought advisable, preliminarily, to give a general statement as to occurrence, and tentatively to list the species.

OCCURRENCE

The mammalian fossils, numbering approximately 150 specimens, were all obtained within a small area located in the NW 1/4 of sec. 14, T. 27 N, R. 11 W, San Juan County, New Mexico. The specimens were collected from a zone of reddish silt three to four feet in thickness. The actual bone layer, not as yet located, may prove to be thinner than this. Almost all the material was recovered from approximately 100 linear yards of outcrop. A few specimens, however, were obtained at varying distances away from this central area, as far distant perhaps as one-half mile. Of these, nineteen were at the same level stratigraphically, and only one was lower (by 70 feet) in the section. This latter specimen, representing a new genus and species of Primates, is not certainly duplicated by material at the main concentration. Seemingly, the others are.

* * * * *

The red zone at the "bone pocket" carries many concretionary masses which frequently contain the fossil specimens. Not all specimens, however, are from such lumps.

Even within the area of greatest concentration, specimens are of sporadic occurrence. A low ridge, a few feet high, may have abundant material weathering from the rock on one slope, but have the opposite side barren. Occasionally, a small rill three or four feet in length and six inches or so across may carry fragments of five or six individuals representing several genera. For example, in one such rill were found Didymictis, n. sp. b; Goniacodon levisanus; Tricentes cf. T. subtrigonus; and Protoselene opisthacus. No specimens were found in place in unweathered rock, but the quarry possibilities of the bone pocket have still to be tested.

The stratigraphic position of the bone concentration in relation to the total Nacimiento section exposed in Kutz Canyon has not been determined. It is approximately 160 feet below the western rim at a point nearest the "pocket". The upper 100 feet of strata consists of sandstone believed by Granger (1917:822) to represent either: (1) equivalent of the "Wasatch" (San José) of the Ojo Alamo section, or (2) "Torrejon" (upper Nacimiento). Granger perhaps favored the first interpretation, but the writer, at present, thinks the second probable.

THE MAMMALIAN FAUNULE

Part 2

The following mammalian species have been identified as present in the Angels Peak "pocket".

Order Multituberculata Family Ptilodontidae Mimetodon? cf. M. trovessartianus

Order Insectivora Family Palaeoryctidae Palaeoryctes cf. P. puercensis Family Leptictidae Prodiacodon? sp. Family Pantolestidae Pentacodon n. sp. Family Mixodectidae Indrodon malaris

Order Primates Family Anaptomorphidae anaptomorphid? new gen. and sp. (70 feet stratigraphically below level of Angels Peak pocket). ? Primates, gen. and sp. indet.

Order Taeniodonta Family Stylinodontidae Psittacotherium? sp.

Order Carnivora Family Arctocyonidae Tricentes cf. T. subtrigonus Chriacus truncatus Chriacus nr. C. baldwini Deltatherium fundaminus? Claenodon n. sp. Triisodon? sp. Goniacodon levisanus Family Miacidae Didymictis n. sp. a Didymictis n. sp. b

Order Condylarthra Family Hyopsodontidae Mioclaenus turgidus Ellipsodon cf. E. inaequidens Ellipsodon acolytus Protoselene opisthacus Family Phenacodontidae Tetraclaenodon nr. T. puercensis Family Periptychidae Coriphagus encinensis Anisonchus sectorius Periptychus nr. P. carinidens

ANGELS PEAK CENSUS

The total number of specimens for each member (species or genus) of the faunule is tabulated in the list on the page facing, page 7. For the purposes of this list, census, a few of the isolated teeth have been counted as jaws. They were so counted whenever they seemed to be representative of separate, individual animals.

The census-count includes all of the specimens that were identified. The numbers in parentheses, on page 7, refer to those individuals that were found outside of the 100 linear yards or so of outcrop comprising the principal area of concentration of specimens.

+=============================+===========+===========+=============+ | |upper jaws |lower jaws | upper and | | |(isolated) |(isolated) | lower jaws | | | | |(associated) | +-----------------------------+-----------+-----------+-------------+ | Mimetodon? cf. | | | | | M. trovessartianus | | 1 | | +-----------------------------+-----------+-----------+-------------+ | Palaeoryctes cf. | | | | | P. puercensis | | | 1 | +-----------------------------+-----------+-----------+-------------+ | Prodiacodon? sp. | | 1 | | +-----------------------------+-----------+-----------+-------------+ | Pentacodon n. sp. | | 2 (1) | | +-----------------------------+-----------+-----------+-------------+ | Indrodon malaris | | 4 | | +-----------------------------+-----------+-----------+-------------+ | Primates n. gen. and sp. | 1 (1) | | | +-----------------------------+-----------+-----------+-------------+ | ? Primates | | 2 | | +-----------------------------+-----------+-----------+-------------+ | Psittacotherium? sp. | 1 | | | +-----------------------------+-----------+-----------+-------------+ | Tricentes cf. | | | | | T. subtrigonus | 7 | 15 | 4 | +-----------------------------+-----------+-----------+-------------+ | Chriacus truncatus | 1 | 6 | 5 (2) | +-----------------------------+-----------+-----------+-------------+ | Chriacus nr. | | | | | C. baldwini | | 1 | | +-----------------------------+-----------+-----------+-------------+ | Deltatherium fundaminus? | 3 | 1 | | +-----------------------------+-----------+-----------+-------------+ | Claenodon n. sp. | 1 | 1 | | +-----------------------------+-----------+-----------+-------------+ | Triisodon? sp. | 1 | | | +-----------------------------+-----------+-----------+-------------+ | Goniacodon levisanus | | 2 | | +-----------------------------+-----------+-----------+-------------+ | Didymictis n. sp. a | | 1 | 1 | +-----------------------------+-----------+-----------+-------------+ | Didymictis n. sp. b | 1 | 3 | | +-----------------------------+-----------+-----------+-------------+ | Mioclaenus turgidus | 2 | 2 | 2 | +-----------------------------+-----------+-----------+-------------+ | Ellipsodon cf. | | | | | E. inaequidens | | 3 (1) | | +-----------------------------+-----------+-----------+-------------+ | Ellipsodon acolytus | 3 | 11 | 1 | +-----------------------------+-----------+-----------+-------------+ | Protoselene opisthacus | 3 (2) | 3 (2) | 2 | +-----------------------------+-----------+-----------+-------------+ | Tetraclaenodon nr. | | | | | T. puercensis | 5 (2) | 18 (2) | 4 (1) | +-----------------------------+-----------+-----------+-------------+ | Coriphagus encinensis | | 2 | | +-----------------------------+-----------+-----------+-------------+ | Anisonchus sectorius | 4 (2) | 8 (2) | | +-----------------------------+-----------+-----------+-------------+ | Periptychus nr. | | | | | P. carinidens | 3 (1) | 3 (1) | 2 | +-----------------------------+-----------+-----------+-------------+ | Totals | 36 | 90 | 22 | | | | | 148 | +-----------------------------+-----------+-----------+-------------+

ENVIRONMENT

The faunal list is rather long for one obtained from such a restricted area. It is not exceptional in this regard, however, for even longer lists have been made from single quarry sites in the Paleocene (Simpson, 1937:33-34). The exact number of genera and species represented is still uncertain. It seems that twenty-one genera and twenty-four species are present and that they are distributed among eleven to twelve families and five to six orders. A greater number of genera and species may be recorded eventually.

The ferungulate cohort constitutes most of the fauna (91 percent), and this fact indicates a floodplain facies as the most probable depositional environment. The small representation of multituberculates, insectivores, and insectivore derivatives, however, may be attributed in part to the difficulties inherent in surface collecting of minute specimens.

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