Bursa californica: a fossil and modern-day gastropod

Bursa californica (Hinds, 1843) is a modern-day, shallow-marine gastropod (ocean snail), whose fossil record goes back to the early Pliocene (about 3 million years ago).

Genus Bursa Röding, 1798 belongs to the small family of large sea shells called Bursidae. Their common name is "frog shells" because the intersection of spiral and transverse ribs can result in a strong nodulose pattern of many knobs, producing a "warty" or "frog skin" appearance.

Bursa californica, also known as the "Californian Frog Shell," is characterized by having mostly two protruding ridges (varices) along the left and right margins of the shell. Nevertheless, the warty appearance is not evident on this particular species. 

Bursa californica is found from Monterey, along the central coast of California, to the Gulf of California, mainly in offshore waters. The animal lives mostly on silty-sand bottoms in depths of about 60 to 350 feet. They are active predators and feed on bristle worms (polychaetes), which they anesthetize with acidic saliva. After a storm, some of the shells can wash up on an adjacent beach. The shell is tan-cream in color with a whitish aperture (opening).

Apertural view (front) of a modern specimen
(9 cm height) from Mexico.

Abapertural view (back) of same specimen

Apertural view of a fossil specimen
(8 cm height) from Palos Verdes Sand,
late Pleistocene, Playa del Rey,
 southern California.

Abapertural view of same specimen.

Top view of spire of same specimen.

A growth series (juvenile to adult) of fossi specimens

of Bursa californica from Palos Verdes Peninsula, southern California.

Specimens 2.7, 5 cm, and 8 cm high.

California's Official State Dinosaur

In 2017, the State of California declared its official state dinosaur to be Augustynolophus morrisi Prieto-Márquez et al. (2014), a duck bill of Late Cretaceous age. Duck bills are classified as hadrosaurs.

The generic name, Augustynolophus Prieto-Márquez et al., 2014, is a combination of the Augustyn family, who helped support the Los Angeles County Museum of Natural History, and the suffix “lophus,” in reference to its similarity to Saurolophus, another duckbill, 30 to 40 feet in length, bipedal, and with a battery of flat teeth used for chewing coarse vegetation.  

Augustynolophus, like Saurolophus, has a bony, spikelike crest that projects up and back from the top of the skull. This spike is an extension of the nasal bones.

Augustynolophus morrisi is of late Maastrichtian age, about 68 million years old. The geologic time diagram below depicts the recognized intervals of time that constitute the Late Cretaceous. The Maastrichtian was the last stage of the Late Cretaceous. The red star indicates the approximate occurrence of this dinosaur.

The bones of A. morrisi have been found in the Moreno Formation along the west side of the San Joaquin Valley, Fresno County, central California.

In terms of vertebrate (back-boned) fossils, the Moreno Formation is mainly known for its marine-reptiles (plesiosaurs and mosasaurs). It also contains marine-mollusk fossils (oysters, other bivalves, and gastropods). Augustynolophus morrisi lived in a  marshy, coastal area.

Augustynolophus morrisi is endemic (only found) in California.

For excellent copyrighted pictures of this dinosaur, also known as "Auggie," just "Google" its scientific binomial (two-part) name.

The species name, morrisi, is in honor of the late William J. Morris (1923-2000), a highly respected vertebrate paleontologist who had many dinosaur and other vertebrate-fossil discoveries on the west coast of North America, especially in Baja California, Mexico. His final teaching position was at Occidental College in the Eagle Rock neighborhood of Los Angeles, California. He was also a Research Associate in Vertebrate Paleontology at the Natural History Museum of Los Angeles County.

If you want to see  the entire list of official California names of other geologic entities, go to <en.wikipedia.org>, and click on the associated thumbnail images in order to see larger images.