WESTERN POND TURTLE:MORE THAN MEETS THE EYE

This post concerns Actinemys pallida, the so-called “southwestern pond turtle” but does not include its northern relative, A. marmorata, which is confined to British Columbia, Washington, Oregon, and northern California.

Actinemys pallida is restricted to southern California and Baja, Mexico. It is a species that is vulnerable (i.e., threatened by human activities). This turtle species lives in both permanent and intermittent lakes and marshes, where it feeds on aquatic insects, crayfish, tadpoles, small fish, and small frogs. 

The classification of A. pallida is:

Kingdom Animalia

Phylum Chordata

Class Reptile

Order Testudines

Family Emydidae

Genus Actinmys

Species A. pallida 

Actinemys pallida shown here are about an estimated seven to eight inches long (with its head extended), and having  a dark-colored upper shell (carapace). This turtle is referred to as a “basking turtle,” because on sunny days, it leaves the freshwater source, crawls a short distance on the bank, and then basks in the sunlight.

The geologic record of the earliest known fresh-water turtles is very poorly known, with generalizations and speculations readily available online. The the most often-mentioned geologic time for the earliest fresh-water turtles is either the late Permian, Triassic, or the late Cretaceous. Amid all this confusion, it is pertinent to mention the recent discovery of fossil remains of soft-shelled turtles and pond turtles (as well as abundant alligator fossils, tapirs, brontotheres, etc.) in lower Eocene rocks on Elsmere Island, in Canada’s high-arctic area (see Eberle and Greenwood, 2012). These turtle fossils might well be one of the earliest confirmable geologic recordsof pond turtles.    

Figure 1. Actinmys pallida, oblique left-side view showing white band on cheek and yellow pastron (ventral side of carapace). Estimated length of entire animal: 7 inches.

Figure 2. A. pallida, oblique right-side view showing yellow ventral side of carapace. Estimated length of entire animal: 8 inches.

Figure 3. A. pallida, frontal view showing yellow ventral side of carapace, as well as yellow stripes on neck. Estimated width 4.5 inches.

REFERENCES CONSULTED

Ebele, J.J. and D.R. Greenwood. 2012. Life at the top of the greenhouse Eocene world-a review of the Eocene flora and vertebrate fauna from Canada’s High Arctic. Geological Society of America Bulletin, Jan/Feb 2012:124, no. 1/2, pp. 3-23. [This is not a free pdf].

Reid, K. and three others. 1967. Golden Nature Book “Pond Life”: A guide to common plants and animals of North American ponds and lakes. Western Publishing Co., New York, 160 pp.

GAZANIA FLOWERS: A POPULAR HEARTY PLANT

Its classification is:

Kingdom Plantae

Order Astales

Family Asteracea (this is the daisy family)

Genus Gazaania

Species G. rigens

Gazania belongs to a family that is native to southern Africa, namely South Africa and Mozambique.

Many of the species of this plant are hard to distinguish from one another; therefore, the number species varies widely depending on the specialist worker. In 2009, a much-needed molecular phylogenetic analysis revealed that many of the so-called species of this plant are not really separate from one another. They form a species complex, consisting of about 16 recognized living species (Howis et al., 2009). The flowers of these plants come in various colors, with yellow and orange shades being the most common.

Gazania flowers are easy to grow. They thrive as ground-cover, when growing in full sunlight. A single plant can live for several years because Gazania is a perennial plant. They “come back,” year after year, via their seeds (“it reseeds” itself). They are hearty and drought-tolerant, and they prefer low altitude, temperate regions. They only rarely live in tropical areas. 

Their flowers “close” up at night and during cloudy days. The abundant petals on the flowers have a dark starburst or ring pattern of black dots surrounding their golden center.

If ingested, all parts of this plant are poisonous to humans. Nevertheless, herbivores, like rabbits, squirrels, and deer eat them.

The fossil record of this plant is poorly known. Apparently, it dates to to Pleistocene time (Willis and Niklas, 2004).

Figure 1. Two typical color varieties of Gazania flowers.

Figure 2. Some additional color varieties of Gazania flowers.

Figure 3. Tanzania flowers "close up"in the late afternoon and early morning, when the sun's radiation is not very strong. 

References Cited:

Howis, S., N. P. Barker, and L. Mucina. 2009. Globally grown, put poorly known: species limited and a biogeography of Gazania Gaertn. (Asteraceae) inferred from chloroplast and nuclear DNA sequence data. Taxon 58(3):871-882.

Willis, K. J. and Niklas, K. J. 2004. The role of Quaternary environmental change in plant macroevolution: the exception or the rule? Philos. Trans., Series B 359:159–172.  

THE MINERAL EPSOMITE: MORE INTERESTING THAT ONE MIGHT THINK

The chemical composition of epsomite is MgSO+7H2O (= hydrous magnesium sulfate). The familiar name of this mineral is “epsom salts,” which can be purchased in small bags at any grocery store or drugstore. This mineral is a medical aid. 

Epsomite occurs in near or near salt-lake environments, on walls of mines (as an efflorescence coating), or in association with stalactites and botryoidal masses in caves. It occurs either as crystals, granular crusts, and fibrous aggregates. This mineral is also present in seawater and is the second most common compound found in it, after sodium chloride.

Also, epsomite may exist in the soils found on the planet Mars. 

Well-formed (i.e., not crowded) crystals, grown under controlled conditions, are clear and have shapes diagnostic of the orthorhombic mineralogical system (e.g., diagnostic type of faceted ends on the ends of the crystals) (see Figure 1 shown below). Commercially available bags (e.g., sold in drugstores) of this mineral, however, contain material derived from fast, raw-mining techniques. These particular crystals are porcelain-like, white, and have been mechanically crushed.  If they show any symmetry at all, it is a simple prismatic (tabular) shape. The hardness of this mineral is 2 to 2.5 (see Figure 2 shown below).

The clear crystals shown below in Figure 3 were grown in situ, by me. I took a small amount (about a tea-spoon) of the commercially available material and dissolved it in a small amount (about 30 ml) of water for a few days. Eventually, the water evaporated, and the resulting crystals came out clear and with mineralogical symmetry. It is best not to put too much material into the water. Then let the solution sit, undisturbed, for a few days. The results (shown below) are astonishing!

Reference Cited:

Berry, L.G. and B. Mason. 1959. Mineralogy concepts, descriptions, determinations. Freeman and Company, San Francisco. 630 pp.

                                                 FIGURES

Figure 1. Sketch of an idealized acicular/rhombic prism crystal of epsomite (based on fig. 251, p. 98, of Berry and Mason (1959). 

Figure 2. Crystals (up to 3.5 mm long) from a drugstore bag of crushed epsomite. If you look carefully, you can see hints of the original faceted crystal shapes on a few of the crystals. It is interesting to note, that after putting this material into water, letting it dissolve, and eventually letting the water evaporate and allowing new crystals to form, the white, dull luster automatically disappears!

Figure 3. Ten “home-grown” crystals of epsomite. The biggest crystal is 27 mm long, 4 mm wide, and 2 mm thick. The shortest crystal is 11 mm long and 2 mm wide.

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.