Peter U. Rodda

The Albian-Cenomanian boundary in northern California

There is no internationally agreed-upon stratotype for the Albian-Cenomanian (Lower Cretaceous–Upper Cretaceous) boundary. Type sections in France for the Albian and Cenomanian Stages are inadequate for this purpose. The proposed boundary stratotype sections in North Africa and Texas that were discussed in Copenhagen at the 1983 Third International Symposium on the Cretaceous System (Birkelund et al., 1984) are inadequately documented, facies restricted, or both. The widespread occurrence of the ammonites Stoliczkaia and Mortoniceras in the upper Albian and of Mantelliceras in the Cenomanian classically bracket the boundary and must be used until the boundary is formally defined. Recent work in North Africa (Robaszynski et al., 1993) promises an Albian-Cenomanian boundary definition based on lineages within these taxa. The ammonite-based Albian-Cenomanian boundary in northern California is between the last occurrence of the typically Albian genera Mortoniceras and Stoliczkaia and the entry of mantelliceratine juveniles (probably Graysonites) associated with Mariella. Pseudouhligella japonicum , heretofore regarded as a Cenomanian indicator in Japan, Alaska, and California, occurs in California in upper Albian and lower Cenomanian faunas. The boundary sequence in California is best exposed along Dry Creek in northern Tehama County, where an angular relationship within the Budden Canyon Formation, resulting from channel cutting on deep-sea fans, separates upper Albian ammonite-bearing rocks of the Chickabally Member from Lower Cenomanian ammonite-bearing rocks of the Bald Hills Member. Although angular relationships and coarse-grained strata of the lower Bald Hills Member are present in the boundary interval, no known ammonite zone is missing. These relationships are interpreted to mean that relatively continuous sedimentation occurred during the Albian–Cenomanian transition and reflect rapid uplift and erosion of a sedimentary, volcanic, and plutonic terrane to the north and east and, perhaps, accompanied by rapid sea-level changes. Collation of the ammonite biostratigraphy herein with previously established foraminiferal and radiolarian biostratigraphies for the Dry Creek sequence suggests that it is a prime Pacific-rim reference section for faunas in the Albian-Cenomanian boundary interval and that previous correlation of the uppermost Chickabally Member with the Cenomanian is incorrect, as Albian and Cenomanian stages are currently understood. This affects correlation and changes the dating of some units in California in the Franciscan Complex from Cenomanian to Albian.

A NEW WORLD OCCURRENCE OF NOTIDANODON LANCEOLATUS (CHONDRICHTHYES, HEXANCHIDAE) AND COMMENTS ON HEXANCHID SHARK EVOLUTION

Notidanodon lanceolatus Woodward is reported from Late Aptian strata of northern California. This specimen, the oldest fossil cow shark (Hexanchidae) in the New World, greatly extends the geographic distribution of this species and confirms the eurytopic distribution of this genus. We suggest that cow shark teeth evolve in an orderly sequence in which the mesial edge of the tooth is at first smooth (Notidanus muensteri), then serrate (Notidanus serratus, Notorynchus aptiensis), and finally dentate (Notidanodon lanceolatus).

Two occurrences of the genus Pictetia (Early Cretaceous, Albian, Ammonoidea) in California

r-TWO specimens of the Cretaceous genus Pictetia Uhlig, 1883, have been found in the Cottonwood District, northern California, the first record of this genus in North America. The larger specimen is a septate whorl fragment from the Brewericeras hulenense zone that is associated with Douvilleiceras mammillatum. It is identified as Pictetia sp. The smaller specimen is a septate fragment of one and a half whorls from the Oxytropidoceras packardi zone associated with Cleoniceras. It is identified with the type species, Pictetia astieriana Orbigny, 1842, previously recorded from Europe. A review of the genus Pictetia suggests that species assigned to the genus have an open coil with a rounded dorsum. The occurrences of these Tethyan elements in the Albian fauna of the Cottonwood District suggest easy communication for many Cretaceous taxa between northern California and the Tethyan realm of Europe, the Caucasus, and Madagascar.

An Early Cretaceous ornithopod dinosaur from California

ABSTRACT Fossils recovered from the late Aptian portion of the Budden Canyon Formation of northern California represent the oldest dinosaur remains known from the Pacific Slope of North America. Eight well-preserved elements, including most of the lower left limb and pes, belong to a small ornithopod dinosaur that is similar to the hypsilophodontids Parksosaurus and Hypsilophodon, although they may represent a new taxon. The late Aptian age, documented by ammonites found in association with the vertebrate remains, suggests that this specimen is probably 20–30 million years older than any dinosaur previously known from the western margin of North America.

A new heteromorph ammonite from the Barremian (Cretaceous) of California

The fauna of the lower Chickabally Member of the Budden Canyon Formation, a part of the Cretaceous Great Valley Sequence in the Cottonwood District (Figures 1, 2) of northern California, was described by Murphy (1975). At that time, two specimens of the species described here were known, but they were not complete enough to be identified or classified. Recently, Embree collected three additional specimens from the same horizon that enable us to classify the taxon with the Heteroceratidae. However, the rate of whorl expansion of the cross section of the conch and the open coiling are different from all other Heteroceratidae and we regard it, like much of the associated fauna, as a genus and species endemic to California.

PRESENTATION OF THE HARRELL L. STRIMPLE AWARD OF THE PALEONTOLOGICAL SOCIETY TO CLARENCE M. SCHUCHMAN

It has been a wonderful pleasure for both of us to have known Mr. Clarence Schuchman for the last 25 and more years. During that time, Clarence accompanied both of us on many glorious outings into the hot and rugged Sacramento Valley and Cascade foothills of northern California in the search for Cretaceous ammonites, and he introduced or accompanied us to several areas that paleontologists and geologists had never visited nor mapped. Born in 1916 on a 3/4-section homestead near Cutbank, Montana, Clarence grew up in the rugged outdoor setting of the Rocky Mountains. He received his BA in Music from Washington State College, in Pullman, in 1938. Clarence soon after was accepted for graduate study in Philosophy and Divinity at the Garret Theological Seminary on the Northwestern University Campus in Evanston, Illinois. In 1940 he was married to Alice Burke. Personal automobiles and gas were scarce at the time because of the war. Clarence and his young wife were adventurous, to say the least, and decided that for their honeymoon that fall it would be fun to ride their bicycles from the west coast back to Evanston for the continuation of his studies. Amazingly, they set off without a single spare tire or tube and made the trip nearly without mishap, save for one emergency delivery of tire and tube by overnight rail near Duluth, Michigan. Clarence received his Bachelor of Divinity from Northwestern in 1942 and this was followed by a two-year stint as an ordained minister in Michigan and then in northern California. After leaving the ministry, he started a small woodworking business, making handcrafted items from native woods in northern California. Not too long after this, he settled into a lifelong career of teaching, both elementary and high school students, until his retirement in 1980. His …