The Only Cowrie Living On The West Coast of the United States

Neobernaya spadicea (Swainson, 1823) (the “chestnut” cowrie), a member of family Cypraeidae, lives today only from Monterey Bay, Monterey County, California to southern Baja California Sur, Mexico. Cowries are marine gastropods found most commonly throughout the world in warm to tropical, shallow-marine waters. There are approximately 260 living species and many extinct species. Living cowries are among the favorites of sea-sea collectors because the cowrie shell is glazed (highly polished) and can have an array of beautiful colors and patterns. The geologic record of cowries is from the Jurassic to Recent. There are many Cenozoic cowries in the fossil record of the west coast, and most of them lived during times that were much warmer than today in this area.

The cowrie now known as Neobernaya spadicea (Swainson, 1823) was misidentified as to genus [e.g., Cypraea], until 2000, when it was recognized as actually belonging to genus Neobernaya. The fossil record of N. spadicea is Pliocene to Recent.

The following four  images are of a specimen of N. spadices (49 mm length [distance between the posterior and anterior]; 29 mm width; and 24 mm height [distance between the base/bottom and the dorsum/top]. This specimen was collected in beach drift from a beach in Santa Barbara County, Southern California.

                                                         dorsal (dorsal)  view

                                                  ventral (base/bottom) view

  

                                right-side view (outer lip side)

                                  left-side view (inner lip side)

The name “spadicea” refers to the chestnut-brown color although there is a variation of the color of the top surface of the shell of this species: from chestnut brown to rust to red. The base (lower surface) and lower parts of its sides of the shell, however, is white.

This species lives in moderately cool waters, from intertidal to 50 m depth, especially the sublittoral zone near ledges and rocky areas. It lives in the near vicinity of forests of the giant kelp Macrocystis pyrifera, where this gastropod preys on bryozoans, hydroids, sponges, anemones, tunicates, and molluscan eggs. At least one of octopus apparently feeds on N. spadicea.

After hatching from eggs, the young of N. spadicea transition into a free swimming stage (veliger), but they are slow swimmers and many settle quickly to the ocean floor and begin to grow into adults. The juvenile stage of this species, like all cowries, is called the “bulla” stage. Its shell is very thin and elongate. Eventually, this stage will transition into the glazed over, strong shell of an adult. The maximum, full adult shell size is about 80 mm length.

Interior of a N. spadicea specimen showing the juvenile bulla stage. The entire specimen (length 46 mm, width 27 mm) was collected also as beach drift from a beach in Santa Barbara County, Southern California.

Much of the information used in this post is from the following very useful and up-to-date reference:

Groves, L.T. 2019. The family Cypraeidae Rafinesque, 1815, in the northeast Pacific: One spectacular species. Zoosymposia 13:131–138 (James H. McLean Memorial Volume).   

An Eocene volute gastropod from the Llajas Formation of southern California

This post focuses on a middle Eocene (about 48 million-years old) shallow-marine gastropod belonging to the family Volutidae. The term "volute" is a shortened term, referring to this family.

Eocene volutes are not that common in the coastal area of California, Oregon, and Washington. Locally, however, specimens can be found but usually require persistent collecting. An example of one of these volutes is a species of Lyrischapa from middle Eocene beds in southern California.

The scale in all the photographs has centimeter increments. The largest specimen shown below is 5.5 cm in height, but this specimen is somewhat incomplete.

All the views are of the back (abapertural) side of Lyrischapa lajollaensis (Hanna, 1927). These specimens show a growth series, from juvenile to adult size. The second largest  specimen has many boreholes made by boring algae or sponges. 

Front (apertural) views of Lyrischapa lajollaensis (Hanna, 1927): these are three of the same specimens (the second, fourth, and fifth ones) shown in the preceding image.

Genus Lyrischapa had wide distribution in the world during the Paleocene and Eocene, when warm-shallow seas were widespread. 

The cephalopod Spirula spirula and its interesting relatives

This post, and the following two posts, concern the coleoid cephalopods.

Cephalopods, which are the most specialized of the mollusks, are characterized by having a distinct head, arms, and tentacles. They are exclusively marine, and most are distinguished by their chambered shell although some of the more modern ones, however, have a reduced internal shell or no shell at all (octopus).

The main divisions of cephalopods are: ammonoids (including ammonites), nautiloids, and coleoids.

The main divisions of coleoids are belemnoids, spirulids (genus Spirula), sepiids (genus Sepia), squids, and octopods (octopus). In an earlier post, I focused on the subject of the belemnoids (an extinct group, which was dominant during the Jurassic and Cretaceous). The other coeloids are highly diversified and because they have a pair of gills are referred to as dibranchiates, which are mainly Cenozoic forms and their fossil records are poor. The following forms exemplify them.  


Spirula spirula (Linnaeus) is the only living member of this genus of spirulid coleoids. It lives as a free-drifting animal in deep seas of the world's warm oceans. Dead shells can be found on beaches. Spirula has a coiled chambered shell (phragmocone), but the walls of each coil do not touch the previous coils. The closely spaced chambers (septa) of the shell have a thin tube (siphuncle) extending through them via a ventral perforation. This tube allows for transport a gas used for buoyancy. The shell is carried internally, near the posterior end of the animal. Unlike the pearly Nautilius shell (see my August, 2016 post), there is no large, final body chamber.  

The internal chambered shell of Spirula spirula from Florida.  Maximum diameter of this shell is 2.3 cm.

Same shell as shown above;  interior of the last chamber (6 mm width), showing the perforation for the siphuncle. 

The fossil record of the early coleoids is sparse, therefore, there are many challenges in trying to unravel the evolution of this group because the degree of coiling differs dramatically.  Two very rare Eocene specimens are shown below: 

This first specimen consists of two fragments of the same specimen from the Llajas Formation in southern California is middle Eocene. The two fragments together are 23 mm in length.

This schematic diagram shows an inferred reconstruction of the Llajas Formation specimen shown above and its tapering but straight (orthoconic) phragmocone with chambers. For more information, see Squires, R.L., 1983. New mollusks from the lower middle Eocene Llajas Formation, southern California. Journal of Paleontology 57(2):354-362.

This other specimen is of late Eocene age from the Hoko River Formation in the extreme northwest corner of Washington State (in the Strait of Juan de Fuca. The image shows the dorsal view of the 20 mm length of the hoof-like shell. In its posterior area, the chambers of the phragmocone are much smaller and are tightly coiled, versus the later chambers.  For more information, see Squires, R.L. 1988. Cephalopods from the late Eocene Hoko River Formation, northwestern Washington. Journal of Paleontology 62(1):76-82.

Cone Shells: Past and Present

“Cones” or "cone shells" are common names for a large group of marine gastropods, whose shell is shaped like a geometric cone. Current sources say that there are between 500 and 800 species of modern cones. Their classification has been in a state of change during the last decade because of new information based on DNA studies of their soft parts.

Cone shells, which can have beautiful color patterns, have been traditionally very popular among shell collectors. If the species is rare, like the one shown below, specimens can be very expensive to purchase. Conus gloriamaris, the so-called "glory of the sea" is a prime example. About 35 years ago, it was considered to be vary rare, hence it was highly priced and worth thousands of dollars. Then many new specimens were found, and the price went way down, to hundreds of dollars.

Conus glorimaris (height 9 cm), West-Pacific region, both shallow and deep-marine depths.

Cones have their greatest diversity in the Western Indo-Pacific region, but a few species have adapted to warm-temperate (coolish) environments, like that found in southern California. Conus californicus is the only cone found today on the west coast of the United States. It is common as beach drift on southern California beaches in Ventura County. This species also has a fossil record in this same area.

Conus californicus (biggest specimen is 3 cm height, Ventura County beach drift, southern California). These shells have been smoothed somewhat by wave action during transport along a beach.

Ancestral cone shells most likely preyed on marine worms because the majority of living cones are vermivorous, that is to say, they  feed on polychaete worms or other worms. During the Miocene (about 15 to 20 million years ago), it is likely that some cones began to hunt for mollusks and fish. This resulted in an explosive adaptive radiation, with an increasing number of cones resorting to these more specialized feeding strategies. Today, there are some cone shells that have retained ancestral feeding habits by preying on worms, but these cones can resort to feeding on mollusks or on fish. One example is Conus tessulatus. It is known to be able to spray venom near the gills of fish, thereby possibly immobilizing them. This technique, however, is not always successful.

Conus tessulatus (4.5 cm height, Seychelles Island, Indian Ocean), a less-derived (in an evolutionary sense) cone. 

Modern cones have developed more effective techniques of delivering venom to their prey. One way, which is used by C. marmoreus (see photos below) is to use a hollow harpoon-shaped tooth that can be injected into a fish. As soon as the fish is paralyzed, the cone "reels" in the fish. Other cones inject extremely toxic venom, and the fish is paralyzed almost immediately.

Conus marmoreus (7.5 cm height) Indo-Pacific region. This a common cone shell, whose shell is thick and heavy. 

Cone toxins are aptly named conotoxins, which are complex cocktails of neurotoxic disulfide-rich peptides. Some of these cone toxins are lethal to humans, thus you should never handle a live cone.

Conus textile (6 cm height, Indo-Pacific region, shallow depth). This is a "deadly" cone, which injects its victims via sharp darts.

Conus geographus (height 9 cm, Indo-Pacific region, shallow water). This cone is well known for its very toxic venom, and some say it is the "number one" most toxic cone. Even predators of mollusks avoid this shell! As a result, the shell of C. geographus is light and thin, unlike nearly all other cone shells.

Cone shells have a fossil record extending back to the Eocene, about 50 million years ago. They had a cosmopolitan (globally widespread) distribution at that time, including occurrences in southern California, southwestern Oregon, and southwestern Washington. Eocene cones are smaller in shell size than most modern cones.

Conus californianus (1.7 cm height, middle Eocene Tejon Formation, southern California). The drill hole in this shell was most likely made by a boring gastropod, belonging to the noticed family.

Conus cowlitzensis (3.6 cm height, late middle Eocene Cowlitz Formation, southwestern Washington). This species is similar morphologically to C. californianus and, together, they likely form a lineage.

Beale's Cut, Newhall, Southern California

Beale's Cut is a narrow, man-made gap through a ridge near the town of Newhall, in northern Los Angeles County, southern California. This gap (or pass) dates back to 1854, when Phineas Banning dug out a 30-foot gash, in order to allow horse-drawn wagons and stagecoaches to travel through a narrow canyon whose head was blocked by solid rock. The gap occurs in an area that has had a succession of names: Fremont Pass, San Fernando Pass, and more, recently, Newhall Pass.

On the approach to Beale's Cut in April, 1985.
(the view is to the northeast)

Beale's Cut, April, 1985, with a partial silhouette of a person
 and a chain-link fence, for scale.

Beale's Cut, April, 1985.

 Google Earth (2018) image showing a

 bird's eye (vertical) view of Beale's Cut.

In 1861, Edward Fitzgerald Beale deepened the gap to 90 feet in height, thus allowing even better passage to places like Fort Tejon, to the north. At that time, the gap in the canyon became known as Beale's Cut. It was used for vehicles until 1910. It was also used for many silent westerns and was where the American actor Tom Mix and his horse allegedly "jumped the gap," in the movie "Three Jumps Ahead."

Beale's Cut is still in existence, but it suffered during the Northridge Earthquake in 1994. Today, it is only 30-feet deep again because of infilling by rock falls. 

It is located just off of Sierra Highway, which is west of Interstate 14. Spotting if from the road level is difficult. Along the side of Sierra Highway there is a small monument/plaque, but the entire area is fenced off now in order to reduce vandalism and trash dumping. There is no place to turn off the road to park your car. 

The gap occurs in the Saugus Formation, a Pleistocene fluvial (ancient river) sandstone deposit associated with the erosion of the adjacent San Gabriel Mountains.

Two Late Cretaceous species of the bivalve Pterotrigonia

In some cases, recognition of two species of the same genus can be problematic. In the examples shown here, however, the recognition  is straightforward. The species are of a shallow-marine bivalve (clam) of Late Cretaceous age from the west coast of North America. These species lived as burrowers in subtidal shelfal depths.

Pterotrigonia klamathonia, 4.5 cm length, Santa Ana Mountains,
Turonian age, Orange County, southern California.

Pterotrigonia klamathonia (Anderson, 1958), which is of Turonian age, is characterized by its closely spaced radial ribs, 20 to 25 in number.

Pterotrigonia evansana, 4.5 cm length, Campanian age,
Simi Hills, Ventura County, southern California.

Pterotrigonia evansana (Meek, 1858) is geologically younger and is of Coniacian through Campanian age (see time table below). This species is characterized by its widely spaced radial ribs, commonly 10 or so in number.

Genus Pterotrigonia, which is the state fossil of Tennessee, is extinct. This genus belongs to the family Trigoniidae, whose geologic time range is latest Jurassic through the end of the Cretaceous. The family was very widespread in the world during the Cretaceous.

Epidote (the coating form)

Ever since I started collecting minerals, I noticed green splashes of a material coating various pieces of granite and other various rocks. I learned later that the coating consists of the common mineral epidote (pronounced “ep-i-dote”).

Epidote is a calcium, aluminum, iron, hydroxyl-silicate mineral typically found in metamorphic-rock areas where alteration or replacement took place in association with hydrothermal fluids. Epidote is especially common in fractures or joints. Fibrous crystals of epidote can be dark-green, black, or even yellow.

The epidote I find, however, has a very distinctive pistachio or pea-green color. It occurs primarily as surface coatings on cobbles and boulders of biotite-rich granite, which weather out from sedimentary rock conglomerates, as shown below. The name “epidote” is derived from a Greek word meaning “increase,” in reference to its crystalline shape.

Epidote coating a clast (maximum dimension 5 cm) of granodiorite
found on a hiking trail in the Santa Clarita area, Los Angeles
County, Southern California.

Trigonarca californica

This post concerns a common Late Cretaceous bivalve (clam) that lived in California approximately 92 million years ago (Turonian time). It is Trigonarca californica Packard, 1922, which is known from northern California (Siskiyou County) to southern California.

The specimens shown below are from the Santa Ana Mountains of Orange County, and they were collected from the Baker Canyon Member of the Ladd Formation. As this locale, where specimens can be abundant, this species lived in sandy, warm, shallow-marine waters. A collector recently kindly donated these specimens.

Right-hand valve of Trigonarca californcia Packard. Length 4.4 cm.

          

This unusual specimen shows the somewhat separated valves of a formerly closed-valved specimen

of Trigonarca californica Packard. The hinge with its distinctive teeth are nicely preserved. Length  of the left-hand valve (at the front of the photograph) is 4.3 cm.

The sturdy shell of this species has the shape of a rounded triangle. Its teeth (dentition) are distinctive and consist of numerous, relatively heavy, short, straight teeth along its hinge.

Genus Trigonarca, which belongs to family Glycymerididae, was widespread, with occurrences in North America, Europe, South Africa, and India. Trigonaraca is of Late Cretaceous age.

A middle Eocene heart urchin

Heart urchins, also called spatangoids, are echinoderms (sand dollars, sea stars, etc.), which are generally characterized by having 5-rayed (pentameral) symmetry. This post focuses on a middle Eocene heart urchin known as Schizaster diabloensis Kew, 1920. It was named for its occurrence in sedimentary layers near Mount Diablo, just east of San Francisco.

A hand specimen of siltstone rock from the Llajas Formation has three specimens of
S. diabloensis on the same bedding plane. The hand specimen is 5 cm (2 in.) wide.

This species of heart urchin was common in northern and southern California during the middle Eocene (approx. 47 million years ago). The specimens shown here are from the Llajas Formation in Simi Valley, California. This formation was deposited in shallow-marine, warm-water conditions. The entire geologic time range for this species is late Paleocene through middle Eocene.

Five specimens of S. diabloensis from the Llajas Formation. The largest specimens are
  2 cm (0.8 in.) wide. All are top-side up.

Echinoderms, past and present, are strongly gregarious and can occur in great numbers on the ocean floor. Spatangoids have a fossil record extending back to the Cretaceous. They are burrowers and living below the surface provides protection against predators. During the Cretaceous, many new forms of predators evolved, which, which gave the force for some echinoderms (like spatangoids) to adapt to these adverse conditions by becoming infaunal (i.e., burrowers), mainly in fine-grained deposits, like siltstone.

You can readily see the five-rayed symmetry of the feeding grooves on the dorsal (top) surface of each specimen. The central groove, called ambulacrum III, is the longest and is sunken on most spatangoids, whereas the two posterior grooves are smaller. 

Why is massive rose quartz pink?

I have always enjoyed collecting quartz, and massive rose quartz is one of my favorites. There are some interesting new findings about what causes its coloration, and this post with help inform you about some of them. You might note that researchers use the adjective “massive” to describe rose quartz. This is done in order to differentiate it from euhedral (nice, angular crystals) of rose quartz.

A polished specimen of massive rose quartz, 3.75 inches high.

Massive rose quartz is one of the common colored varieties of quartz and found at numerous localities worldwide. A few of the areas where multiple localities are known include: Brazil, California (Riverside County), Montana, South Dakota, Norway, and Madagasgar. Massive rose quartz is commonly found in granitic pegmatities. It is less commonly found in hydrothermal veins.

Unpolished massive rose quartz (about 6.5 inches long), from Minas Gerais mine in Brazil.

So, what causes the pink color of massive rose quartz? Over the years, there have been various explanations, but the one that has been meticulously researched by Caltech mineralogists in recent years has proven the presence of pink nanofiber inclusions, which are related to the pink mineral dumortierite, a boron-bearing silicate. These pink nanofibers are 0.1 to 0.5 micro meters in width [about 0.00002 inches], and they resemble wavy bundles of hair-like fibers.

Massive rose quartz is always slightly to highly cloudy (turbid) and never clear. Its color can range from pale to pink to lavender (even in the same hand specimen, see third picture), and, in some cases, entirely lavender (see fourth picture), or, reportedly, orange.

From left to right: massive rose quartz showing transition from pale pink to pinker to lavender.
Hand specimen is 5 inches in length.

Lavender variety of massive rose quartz.
Hand specimen is 4 inches high.

I obtained much of the above information from the very informative article:  Goreva, J., C. Ma, and G. R. Rossman, 2001. Fibrous nanoinclusions in massive rose quartz: The origin of rose coloration. American Mineralogist vol. 86, pp. 466–472.

Just copy the article title, paste it in the Google Search box, and you can get your own free pdf.

Tejonia moragai

This post concerns the ampullinid Tejonia moragai (Stewart, 1927), a moderately common Eocene shallow-marine gastropod found from southwestern Oregon to San Diego. This gastropod is known only from upper lower to upper Eocene strata (approximately 50 to 38 million years ago).


  

Tejonia moragai is small to medium-size. The above picture on the left is the front or apertural view of an adult specimen (30.7 mm height, 22.6 mm diameter). The picture on the above right is the abapertural or back view of the same specimen.

This gastropod is characterized by having an inflated last whorl that is smoothish but with minute spiral sculpture, a somewhat moderately elevated spire with tabulate (squared-off and indented) whorls, a distinct umbilical pit, and an absence of an umbilical callus. 

If you look at my previous post, which concerns the Eocene Pachycrommium clarki, you will see that T. moragai resembles P. clarki. There are a few subtle differences, thus, in my opinion, the two gastropods are different species. Tejonia moragai is smaller in size, has minute-spiral sculpture (lines), an umbilical pit rather than a slit, and no umbilical callus. The sculpture, however, could easily be worn or weathered away, thereby making the distinction between these two species difficult. The main question, however, is whether they belong to the same genus? An answer  requires a detailed comparative study, which has so far, been wanting.