RARE PULMONATE SNAILS OF EOCENE AGE, SOUTHERN CALIFORNIA

Pulmonates are nonmarine snails and slugs. Some pulmonates are terrestrial (air breathers that live on land), and some live in freshwater. Finding fossils of pulmonates in shallow-marine deposits is rare, and finding their remains in upper lower Eocene-age (40-million-years old) marine deposits is rare.

When I was a professor of geology, one of my principle-research areas was the Eocene Llajas Formation in Ventura County, southern California. After going there for many years, only two pulmonate specimens were found (both from the same locality). The best preserved one of these two specimens is illustrated below, for the first time.

I contacted a pulmonate expert, Dr. Barry Roth (recently deceased), to get his professional opinion as to whether or not these two specimens could be identified as to family/genus. After examining the specimens, he concluded that the two specimens are indeed, pulmonates, but that their preservation does not allow identification beyond the general term “pulmonates.”

Because the two specimens are so rare, I decided to mention them in my blog, in the hope that in the future, more can be deciphered about them.

Fig. 1: Apertural view, 5 whorls present, diameter 25 mm, height 17 mm. The width/height ratio is 1.47.

Fig. 2: Top view of previously shown image, 4 whorls present, diameter 21 mm, height 15 mm. The width/height ration is 1.40.

Fig. 3: Bottom view of previously shown image.

Roth (1988) discussed pulmonates from other similar geologic-age nearshore deposits in southern California. He did not mention, however, of any pulmonate snails having ever been found in the Llajas Formation. 

The depositional environment of the bed in the Llajas Formation (i.e., the “Stewart bed”) that contained the rare pulmonate specimens is shallow-marine and represents a shoreline environment, adjacent immediately adjacent to a deeper water marine environment (Squires, 2022). It seems likely that these pulmonate shells were washed “out to sea” and floated to where they eventual settled out and became incorporated in the sediment.

REFERENCES CITED

Roth, B. 1988. Camanid land snails (Gastropoda: Pulmonata) from the Eocene of southern California and their bearing on the history of the Camaenidae. Transactions of the San Diego Society of Natural History, v. 21(no. 12), pp. 203-220.

 

Squires, R.L. 2022. The earliest Ancistrolepis (Gastropoda: Buccinidae) and its geologic implications. PaleoBios 39(2):1-11, cover + figs. 1-4.

THE AVOCADO: AN INTERESTING PLANT

Avocado fruit (a.k.a. as the “alligator pear”) is well known to grocery-store shoppers. The earliest known fossil record of this fruit is Persea umbrellularia, an early or middle Eocene avocado species found in California (Schroeder, 1968)! This occurrence is a relic of a Caribbean flora because the avocado is native to Mexico and Central America. Thus, if the avocado had a pre-Eocene history (when exactly, however, is yet to be determined).  

The avocado plant likely diversified during the Pleistocene, sometime between 1.3 million and 430,000 years ago. Its fruit was undoubtedly eaten by now-extinct prehistoric mammals, such as ground sloths, glyptodonts, and gomphotheres (see my previous posts on these prehistoric animals). The fruit was probably (and still is) also a food source for bears.

The avocado was first “domesticated” by farmers, about 5,000 years  ago, when it became prized for its large and healthy fruit. It grows as a berry tree, with a single very large nut, per fruit. 

The avocado is high in fiber and rich in the vitamins C, E, and K. It is a foliate plant, and is healthy for promoting red-blood cells in the human body. It also contains magnesium and potassium which help to maintain blood-sugar and blood pressure levels. If you are interested in the modern history and/or medicinal aspects of avocados, there are many online videos readily available. 

The classification of an avocado plant is:

Kingdom Plantae

Order Laurales

Family Lauraceae

Genus Persea

Species P. americana

Avocado trees do best in tropical and subtropical climates. [note: many years ago, while doing field work, I came across a sizeable avocado orchard atop the Simi Hills (immediately west of the San Fernando Valley) = a Mediterranean climate in the Los Angeles area of southern California. There were hundreds of trees in that orchard. I think that the orchard has been replaced by new homesites.

From a seed, it takes 5 to 13 years for the avocado to grow into its mature-tree form. These trees can live for 200 to 400 years, but their fruit is only produced in the first 20 to 30 years or so. These trees like to grow in full-sun conditions.

1. Exterior of a “Hass” avocado from Mexico. This avocado” is 3.5 inches (95 mm long) and 2 inches wide (50 mm). Its “skin” is thin (0.5 mm thick) but strong.

2. Interior of the same avocado, with its “meat” present, surrounding the interior nut.

3. Interior of the same avocado, but with the “meat” extracted and the nut fully exposed. The meat occupied about 40 percent of the interior volume of this avocado.

4. Cross-section of a nut extracted from the inside a different avocado. A paper-thin sheath cover around the nut fell apart. This nut is 1.25 inches (28 mm) long and 1.25 inches (28 mm) in diameter. The small seed (5.5 mm length) can be readily seen in the upper part of the image.

Reference Cited:

Schroeder, C.A. 1968. Prehistoric avocados in California. California Avocado Society Yearbook 52:20–34. [online pdf free).

MOUNT FITZ ROY

This mountain is in Patagonia, on the border between Argentina and Chile. It is one of several closely spaced, vertical-granite monoliths that form a very scenic glacial arête (see one of my earlier posts regarding these geomorphic features, which consist of jagged ridge lines formed by glacial-and wind erosion). These  sheer rock towers are located near the village of Chalten and near Viedma Lake.

     South America (Google Earth image)

Location of Mt. Fitz Roy in southern South America

(Google Earth image)

Mt. Fitz Roy area, southern Argentinan (Google Earth image)

Mount Fitz Roy is named in honor of Fritz Roy, captain of the HMS Beagle, who was famously associated with the naturalist/author Charles Darwin. Fritz Roy travelled into the area of southern South America and made maps of a large part of the Patagonia coastline. 

Climbing Fitz Roy, or one of the other nearby vertical towers, is NOT for beginners! The highest tower of this complex is 11,171 feet (3,405 m) in elevation.

                                   

           Panoramic view of Mt. Fitz Roy (the central peak)

The geologic history of Mt. Fitz Roy and the other associated towers is complex. The Pacific tectonic plate was subducted (pushed underneath) the South America tectonic plate. Magma from the Earth’s interior thereupon intruded upward through Paleozoic rocks, solidified and formed granitic bodies. Geologically younger (late Miocene = about 12 million years old) rhyolite extrusives (plutons) also were formed in association with the tectonic forces, and these severely affected the older rocks. Eventually, winds, snow, ice/frost, and melt-waters have severely eroded any exposed rocks. In sum, the eroded remnants visible in the arête today (Mt. Fitz Roy and its satellite peaks) have have undergone a very complex geologic history (Ramirez et al., 2008).

Reference Consulted:

Ramirez, C. and two others. 2008. Magmatic history of the Fitz Roy plutonic complex, southern Pagagonia (Argentina).  Pdf available for free.

AN HERB WITH A FOSSIL RECORD

A plant, known as “borage” [pronounced “bor” “age”], and also known as the “star flower,” is a robust herb, native to the Mediterranean region. It is now well established in Europe and the USA. Two planters in my Southern California front yard are home to several robust concentrations of this interesting plant. The largest concentration reaches a height of 49 inches.

The classification of this plant is:

Kingdom Plantae

Order Boraginales

Family Boraginacae

Genus Borago (pronounced bor-age)

Species B. officinalis

Borago officinalis remains in the garden from year to year via self-seeding (thus this plant is not a perennial). Gardeners like this plant because it repels mosquitos (Wikipedia, 2025).

This plant typically has small “star-shaped” blue flowers, but less genetically dominant varieties of this plant can have red and blue, red, purple, or even white (with a red center) flowers (Wikipedia, 2025). 

Based on associated fossil-land snails and non-marine microfossil plants, the geologic history of Borago dates back to the lower to middle Eocene. These earliest known fossils are found in northern Africa (i.e., southwestern Algeria), according (Hammonuda et al. (2015). 

Diagnostic features of borage (see images below) include its: numerous druppy branches with grayish purple stems. Also,  Some of the ends of these stems bear small, blue-shaped flowers with black stamens at their center. Before the flowers bloom, however, the ends of the stems have a bell-shape and a spiky tip, which eventually erupts into a flower at the end of the branches. The leaves of this plant can be relatively large (up to 6 inches long). The tops of the leaves are textured and have minute spikes. The bottoms of the leaves have prominent veins. Additionally, the bottom of a leaf is more coarsely spiked than is the upper surface.

Figure 1. A clump of druppy branches (field of view 9 inches):

Figure 2. Closeup of druppy branches (field of view 6 inches):

Figure 3. Blue miniflowers (field of view 3 inches:.

Figure 4. Closeup of a single blue miniflower (approximately one-half inch diameter).

 

Figure 5. Front side of a cluster of leaves (field of view 5 inches):

Figure 6. Length of a portion (3 inches long) of the bottom side of a leaf:

Referencs Cited:

Hammonda, S.A. and six others. 2015. Fossil nutlets of Boraginaceae are from the continental Eocene of Hamada of Meridja (southwestern Algeria). The first fossil of the Borage family in Aftica. American Journal of Botany 102(12):2108-2115. [Free pdf that is readily available online].

Wikipedia. 2025. 

A SOUTHERN CALIFORNIA SCARAB BEETLE

Last year, a partly decomposed beetle was found in my backyard garden.  When I identified it as a scarab beetle, I was surprised because I did not think that they lived in Southern California. Although the specimen has lost some of its shiny appearance, it is a boni-fide scarab beetle.

CLASSIFICATION:

Phylum Arthropoda

Class Insecta

Order Coleoptera

Family Scarabaeidae [more than 35,000 species are known in the world today]. 

Genus Cotinis 

Species multabilis

                [Common name: “Figeata beetle”]

COMMENTS ABOUT Cotinis multabilis:

It occurs sporadically in the Los Angeles area. It is usually found in fruit orchards, where it prefers to feed on the pollen, nectar, and flowers of over-ripe fruit plants (e.g., primrose and cactus flowers, etc).  

This species is native to Arizona and New Mexico. It gradually spread to southern California, where it loves to feed on fruit plants in late summer to early fall (Wikipedia, 2025).

CHARACTERISTICS ABOUT SCARAB BEETLES:

1.5 to 160 mm (0.6 to 6.3 inches) in length; it is considered to be large in size.

Stout-bodied

Many have bright metallic colors (velvetly, olive green). Its wing covers are brownish orange (these colors are not well preserved in the specimen illustrated in this blog). 

Distinctive club-head antennae (they apparently fell off of the specimen shown below)

Head region with prominent “horns” for fighting, digging, feeding, etc.

SOME INTERESTING FACTS ABOUT SCARAB BEETLES:

Many species are scavengers.

They are harmless (i.e., non-toxic).

They comprise 10 percent of all known beetles.

They are found on all continents, except Antarctica.

They were venerated by the ancient Egyptians and considered to be sacred.

Scarab beetles have a complicated geologic history associated with the development of angiosperm land plants. The earliest known scarab beetles probably originated during the late early Cretaceous (about 108 million years ago) Ahrens et al. (2014). But, it is possible that scarabs   appeared even earlier, during the Jurassic Period  (Denver Museum of Nature and Sciences). The end result is that they evolved into one of the largest beetle superfamilies with over 35,000 living species

Shown below are three views  (dorsum, left side, and ventral: in that order of appearance, below), of the specimen found in my backyard. The specimen was partly decomposed when found, thus it is not in perfect condition. Its colors are also somewhat faded. This is the only scarab beetle I have even seen in southern California, but they are reportedly common in this area, where fruit trees are growing.

Length 1.5 inche (including wing pads)

Width 0.5 inches

Thickness 0.75 inches (including legs)

As mentioned above, this species likes to feed on the pollen, petals, and nectar of the primrose plant. Shown below is the actual plant (yellow flower 1.5 inches diameter) that the above-photographed beetle specimen was attracted to in my garden.

REFERENCES

Ahrens, D. and two others. 2014. The evolution of scarab beetles tracks the sequential rise of angiosperms and mammals. Proceedings of the Royal Society of Biological Sciences. Vol. 281, Issue 1790. (pdf readily available and free).

Denver Museum of Nature and Sciences. http://www.dmns.org

Hogue, C.L. (revised by J.N. Hogue). 2015. Insects of the Los Angeles Basin. 3rd ed. Natural History Museum of Los Angeles County, 474 pp.

Wikipedia.com

 

THE CALIFORNIA SYCAMORE TREE

For decades, every fall/winter, my front yard in northern Los Angeles County, southern California, has been the collection site for copious quantities of wind-blow leaves. They emanate from a row of trees were planted forty years ago, by the city, on both sides of a street one block east of my house. Of course, most of the leaves do not just simply blow down the street. Instead, they blow south for one block along the street, then they turn 90 degrees and blow west, where they accumulate in huge piles along every “nook and cranky” in my front yard. 

This year, I decided that I would try to identify the genus/species of the trees from which the above-mentioned leaves are derived. This should have been a straight-forward exercise, right? At least, that is what I originally thought. But, as usual, identification of living species can be tricky! Initially, I used pocket “field guides,” but they did not have conclusive illustrations, nor detailed descriptions, that would positively “nail down” the species identification. I had to turn to the internet, and that, too was tricky (almost too much data). Eventually, I came to the inescapable conclusion that leaves were derived from mature California Sycamore trees, namely, Platanus racemosa. Its classification is:

Kingdom Plantae

(Clade) Angiosperms

Order Proteales

Family Platanaceae

Genus Platanus

Species. P. racemosa

[Common name: California sycamore]

Sycamore trees are native to North America. Platanus racemosa lives in southern and central California and, to a lesser degree, as far north as Tehama and Humbolt counties of northern California. They can also be found in Baja California, Mexico.

Note: There are two other species of Platanus found in the United States and surrounding areas (i.e. Platanus wrightii = Arizona  sycamore and Plantanus occidentalis = American” sycamore). Sycamores are also are found also in Mexico and Canada.

Geologic Record of Sycamore Trees: The fossil record of sycamores dates back to about 100 million years, to the Cretaceous Period, 

                                                 Some Shared Characteristics of sycamore trees:

Mature trees can be up to 110 feet tall (35 m) and up to 3 feet (1 m) in diameter. They can live for up to 600 years.

Sycamore leaves are palmate, thus they are shaped like a human hand. These leaves can be very wide (up to about 10 inches).

The leafstalk if hollow (this can be readily seen if you turn the leaf upside-down.

The tree bark peels readily, producing an attractive white, grayish white mottled pattern.

Their fruit consists of “ping-pong” sized balls (achenes), with the seeds in the “furry” interiors of the achenes. The number of achenes) ranges from one to four on a single stem. 

The color of achenes ranges from brown, yellow, yellowish green, or reddish.

The wood of the tree trunk is hard and does not readily split (therefore is used for butcher blocks).

                                                                      

A mature tree of P. racemona found in my neighborhood: 

                        

A different-mottled tree trunk. A mottled tree trunk is typical of sycamore trees.

A dried leaf (5 inches wide), a seed pod (1.25 inches diameter), another

seed pod cut open to reveal its seeds and three individual seeds.

       A leaf with some color retained (front view, 8 inches wide, 10 inches long). The left elongation

     on the lower left part of this leaf is only partial because of breakage. 

Hanging fruit (achene) still attached on one of the trees. The number of achene on a single stem varies from 1 to 4.

 

REFERENCES CONSULTED:

Wikipedia (2025)

Zim, H.S., A.C. Masrtin, and D. and S. Barlowe. 1956. A Golden Nature Guide. New York. 160 pp.

FRESHWATER MIGRATORY BIRDS SEEN RECENTLY IN NORTHERN LOS ANGELES COUNTY, SOUTHERN CALIFORNIA

In late 2025 and early 2026 (i.e. the fall and early winter seasons), I and my oldest daughter, observed the following southward-migratory freshwater birds in two bodies located in northern Los Angeles County, southern California. One of these areas is in a community called Bridgeport (elevation 1165 feet) in, a master-planned community, with water canals next to homesites. The other area is the southern-tip of Castaic Lake (elevation 1151 feet), a large reservoir. Bridgeport is 6 miles (via straight line-bird flight) due southeast of Castaic Lake.

Note: This was our first bird-watching experience. Who knew how interesting birds can be. 

IMAGES OF OBSERVED BIRDS AND COMMENTS

Canada Goose

Branta canadensis

   white area on cheek; dark neck, back, and tail; white belly, body

   length 22-40 inches; weighs up to 18 pounds

----------

Snow Goose

Chen caerulescens 

   white body, black wing tips (white phase); dark body, white head and neck (blue phase)

   body length 24-30 inches

----------

Mallard Duck

Anas platyrhynchos

   male: head and neck glossy green, with white rim

   female: brown  overall, webbed feet

   commonest duck in the world (America, Europe, & Asia)

   body length 16-24 inches

----------

American Coot (the birds, not “old paleontologists”)

Fulica americana  [“fulica” is the Latin word for coot]

   dark, ducklike

   white bill and white-frontal shield, reddish eyes

   grayish-white toes (lobed rather than webbed), green legs

   body length 13 to 15 inches

As a coot swims, it typically “bods” it head. These birds often do short dives after they make a little jump first. The feet of coots are green and not webbed; instead, they have “flaps”/”lobes” on their long and stout toes. These unusual shaped feet aid in their excellent swimming and diving abilities. Coots cannot fly as well as a duck does, but, never-the-less, coots do a good job of flying taking a relatively long start (i.e., runway flapping).

   The fossil record of coots is sparse: from mid-Pleistocene to present day (Olson, 1974).

----------

Western Grebe

Aechmophorus occidentalis

Black cap, gray-black wings, white body

Body length 22 to 30 inches

Good divers

Body length 22 to 30 inches

(closely resembles the double-crested cormorant, see below)

----------

Double-Crested Cormorant

Phalacrorax auritus

Large, dark bird with orange on throat

They eat fish by diving (for relatively long times) for them

Flocks can be mistaken for Canada Geese

Length 2.5 to 3 feet

Good fliers, silent without any “honking”

----------

Great Egret

Casmerodius albus

White bird, neck long and thin (elegant birds)

Bill orange or yellow

Legs and feet black

These birds nest in trees.

Body length 36-42 inches

----------

Green Heron

Butorides striatus

Small size, brownish, red-brown neck, orange legs

Very sharp-pointed orange bill, orange legs

Body length 12-22 inches

This bird can stand motionless overlooking water and can dive.

----------

Birds seen at Bridgeport

based on several trips

Abundant sightings 

American Coots

Mallard Ducks

Canadian Geese

     

Fairly Common sightings

Egrets (white, tall)

Uncommon sightings

Double-Crested Cormorants

Very rare sightings:

Western Grebe

Green Heron

Birds seen at Southern End of Castaic Lake (Reservoir)

based on a single visit

Abundant sightings

Canadian Geese

Uncommon sighting

Western Grebe 

                               ADDITIONAL COMMENTS

 

In the last 25 years or so, the classification of birds, like all living organisms, has undergone significant revisions based on DNA studies, as well as via the re-evaluation of time-honored, physical and behavioral features. In this present blog post, I have incorporated the latest classification information available to me.

 

All birds are classified as Kingdom Animalia, Phylum Chordata, and Class Aves, and numerous orders, families, genera, and species. Currently, there are 23 recognized orders and 9,700 species of birds (Wikipedia, 2005).

Using the online source: worldbirdnames.org, I tried my best to classify, using modern thinking, the freshwater birds (fowl) observed during the field work for this blog post: 

TAXONOMIC GROUPS OF THE OBSERVED BIRDS (ALL OF WHICH ARE ILLUSTRATED ABOVE):

 

PALEOGNATHAE

 ---Gallonaseres 

         Anseriformes (includes many water fowl)

                     Canadian goose

                     Snow goose

                     Mallard duck

 ---Neoaves

          Gruiformes 

                      American Coot

          Podicipediformes

                      Western Grebe

          Suliformes

                     Double-Crested Cormorant

          Pelecaniformes

                     Green Heron

                     Snowy Heron (Great Heron)

Credit:

A friend of my oldest daughter was very helpful in identifying some of the above-mentioned birds.

References Cited: 

North American Wildlife. 1982. Reader's Digest. Pleastantville, New York. 559 pp. 

Olson, S.L. 1974. The Pleistocene rails of North America. Museum of Natural History.

Reid, G. K. and three others. 1967. Pond life. Golden Press, New York, 160 pp.

Sprunt, A. and H. S. Zim. A guide to North American species and their habits. A Golden Nature Guide, Golden Press, New York. 160 pp.

Wikipedia, 2025. 

worldbirdnames.org