Document Type

Dissertation

Date of Award

1974

Keywords

Paleontology, California, Inyo County, Paleontology, Cambrian Paleontology, Precambrian, Proterozoic, Ichnofossils

Degree Name

Doctor of Philosophy (PhD)

Department

Geological Sciences

First Advisor

James R. Beerbower

Second Advisor

James D. Grierson

Third Advisor

Don L. Kissling

Series

Science and Mathematics

Abstract

A stratigraphic collection of ichnofossils and problematic body fossils was made from Lower Cambrian to Upper Proterozoic (sensu Cloud, 1973) strata of Inyo County, California. Specimens were collected from the Wyman, Reed, Deep Spring, and Campito Formations in the White-Inyo Mountains and compared to material from the correlated Stirling and Wood Canyon Formations in the Death Valley area. No recognizable metazoan fossils were observed in the conformable units beneath the Stirling (Noonday Dolomite and Johnnie Formation).

Twenty-five types of ichnofossil are described: Archaeonassa aff. fossulata, ?Arenicolites sp., Arthropod Trace Form A, Beerbowerichnus montenegris (ichnogen. et ichnosp. nov.), Cruziana ��p., Curvolithus Type 1, aff. Didymaulichnus, Dimorphichnus sp., Diplichnites sp., Gordia sp., Isopodichnus sp., Looped Feeding Pattern, Monocraterion cf. tentaculatum, ?Monomorphichnus sp., Phycodes pedum, Plagiogmus sp., Planolites aff. virgatus, Planolites vulgaris, Rusophycus sp., Skolithos ingens?, Skolithos linearis, “Squiggles”, Teichichnus rectus, Torrowangea aff. rosei, and U-shaped Vertical Burrows. Relicts of problematic calcareous fossils (morphologically similar to Cribricyathea) are described, as well as the problematic fossils, Volborthella tenuis Schmidt, and ?Terebellites franklini Howell. In addition, the descriptions of ten sedimentary structures of probable or possible metazoan origin are provided.

Ichnofossils occur in all the formations (Wyman through Campito) examined in the White-Inyo Mountains, but only in the Stirling and Wood Canyon Formations in the Death Valley area. A significant increase in ichnofossil diversity occurs prior to the first appearance of typical Lower Cambrian skeletal fossils. Calcareous fossils, however, do precede this major ichnofossil radiation in both the White-Inyo Mountains and the Death Valley area, and rare ichnofossils are present in strata beneath these problematic shelly fossils. The ichnofossils from the Wyman (assigned to Planolites aff. virgatus) are the oldest metazoan fossil material in the region; they may be separated from the oldest skeletal material by a regional unconformity in addition to most of the thickness of the Reed Dolomite. Structures produced by worm-like creatures (?Annelids) are most abundant, followed in abundance by structures produced by molluscs. Arthropod ichnofossils are usually concentrated at specific horizons.

Ecologically, all major ethological groups (Seilacher, 1953, 1964b) are represented. In this region the earliest benthonic, trace-making metazoans appear to be infaunal deposit-feeders although one problematic specimen, Form B, suggests epibenthonic trace-makers may precede infaunal forms in the Death Valley area.A greater diversity and much greater abundance of vertical domichnial burrows occur in the Wood Canyon Formation than the correlated Deep Spring – Campito strata. In contrast, a greater diversity of fodinichnial (infaunal deposit-feeder) burrows occurs in the Deep Spring – Campito strata compared to the Wood Canyon. The distribution of these ecological types may be related to differences in environmental conditions between the two areas. In both areas traces of deposit-feeding organisms clearly precede the appearance of those believed to have been created by suspension-feeders.

Wiggett (1973) has suggested that the occurrence of ichnofossils and problematic calcareous fossils beneath the oldest Cambrian trilobite fossils in the White-Inyo Mountains may correlate with a pre-trilobite biozone proposed for the Lower Cambrian in other parts of the world. Such a correlation is speculative since no diagnostic pre-trilobite body fossils or ichnofossils have been found in either the White-Inyo Mountains or the Death Valley area. The geologic age of the ichnofossils and the problematic shelly fossils in strata beneath the oldest typical Cambrian body fossils is uncertain.

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