Historical Overview of Late Cretaceous Mollluscan Paleontologists on the west coast

The history of collecting, studying, and naming of Late Cretaceous marine mollusks on the Pacific Coast of North America (PCNA) can be subdivided into three informal groups:

The Pioneers (1860’s to 1890’s):

Gabb, Whiteaves, White, and Cooper were the pioneers. Gabb was, however, the first collector on the PCNA, although Conrad studied PCNA specimens sent to him in Philadelphia. Conrad, who was very knowledgeable about Cretaceous faunas worldwide, never set foot in California.

The Second Wave (early 1900’s):

Among the many examples are Waring, Packard, and Anderson. “The Second Wave” workers explored many geographic areas not covered by the “Pioneers.” “The Second Wave” workers included some university professors, whose students commonly ended up working in the petroleum industry.

The Modern Era (late 1950's to present):

Popenoe (1897–1981), who was mainly affiliated with universities, was the “game changer.” He integrated detailed biostratigraphy into his studies and utilized the same stage names (e.g., Turonian, Campanian), which were used worldwide. He also revolutionized the whole concept of Late Cretaceous gastropod and bivalve studies by establishing lineages based on a good working knowledge of the systematics of many major families of mollusks. He also provided detailed locality information. Popenoe benefited from his association with Takeo Susuki, who collected many specimens and gave expert advice on the principles of photography and scientific illustration. 

                                       Willis Parkison Popenoe III ("Parky") (1879–1981)

Popenoe collaborated also with LouElla Saul. Their discoveries of many new taxa centered on their detailed knowledge of Late Cretaceous mollusks, as well as on their ability to thoroughly and carefully clean the apertures of gastropods and the hinges of bivalves. Without knowing these details, any systematic work borders on/or is largely guesswork.

THE ECHIDNA FROM “DOWN UNDER”

The primitive mammal echidna (also known as the spiny anteater) is a quill-covered monotreme (i.e., a type of ancient marsupial). The echidna, along with the platypus, are the only egg-laying mammals living today. 

Figure 1. Two views (front and left side) of the extant echidna Trachyglossus sp. (an 1863 public domain image).            

Kingdom Animalia

Phylum Chordata

Class Mammalia

Clades (two of them)

Order Monotremata

Family Trachyglossidae

Genus Tachyglossus

Type Species T. aculaeatus  

There are two living genera: Tachyglossus lives in Australia and New Guinea and Zaglossus, which lives only in New Guinea. The former has no known fossil species, but Zaglossus has two fossil species (known only from New Guinea).

The echidna is a quill-covered monotreme-type of ancient marsupial and is an egg-laying mammal. Echidnas are closely related to another egg-laying mammal, namely the duck-billed platypus. These are the only groups of living mammals that lay eggs.

Echidnas do not have a poison spur. They also have no teeth. Although they are unable to bite or chew, they use their long sticky tongues to catch termites. Echidnas are powerful diggers! They do not have a venous spur.

The fossil record of echidnas is poorly constrained, but they apparently evolved from the duck-billed playpus sometime between 112 and 19 million years ago (middle Cretaceous to early Miocene).

THREE SOUTHERN CALIFORNIA FLYING INSECTS

                                          Figure 1. "Crane fly."

Tipula planicornis (has a large-sized body about 1 3/4 inches long) and very long and thin legs. This insect somewhat resembles a very large mosquito, as it has a long body and long legs. It also has brownish wings. It feeds on nectar and is active all year. There are three living species of this crane fly in the Los Angeles area (Hogue, 2015) p. 248).

Figure 2. "Western leaf-footed bug." 

The second insect featured in this blog post is Leptoglossus clypealis, the “western leaf-footed bug.” It is classified as being in family Coridae. This insect is 18-19 mm long. It is brown with a flared [triangular shaped arrow-head like] flat extension on its rear legs. It also has a white, zig-zag band across its wings (Hogue, 2015). This insect is commonly found on Jupiter trees, but it can be a pest on agriculture crops. 

                                   

                                   Figure 3. "Brown Stink Bug"

The third insect featured in this blog is Euschistus servus?, or the “brown stink bug.” It is dark colored, with a “shield-shaped” body. It can grow to a length of 13 mm. It attacks peaches, tomatos, bans, corn, squashi, etc. There are at least 20 described species, and they are active during the day (Wikipedia, 2026). Theses kind of bugs, like the other two species mentioned here are active during the day and can produce  an acrid-smelling vapor which discourages its enemies (Hogue and Hogue, 2025). The geologic time range of “stink bugs,” is early Triassic (250 230 million years ago to Recent (Wikipedia, 2026. 

Reference

Hogue, C.L. [revised by J.N. Hogue] 2015. Insects of the Los Angeles Basin, 3^rd ed. Natural History Museum of the Los Angeles Basin, 479 pp.

GOLDEN RAIN TREE

This tree is unforgettable if you see it in October when the tree undergoes the shedding of its very abundant golden-yellow pollen. That is how this tree got its name: when it sheds its pollen (over several weeks time), the ground beneath the tree is quite yellow and looks like gold dust has “rained down” from the tree. Three species are known, and the one shown here is Koelreuteria bipinnata = the “Golden Rain Tree.” 

Figure 1. Golden rain tree in Santa Clarita, Southern California.

Koelreuteria is native to China, Korea, and Outer Mongonlia (i.e., in both Russia and Mongolia). It has been was cultivated in Japan since at least the 1200’s, and it was introduced to Europe in 1747 and to North America is 1763. It is supposedly now a popular landscape tree worldwide. It is drought-tolerant (once it is well rooted). It is a moderately hardy tree. I had never seen one the until Fall of 2025, when I spotted, in a local municipal park, a 40-foot-tall tree with “clumps” of golden pollen. 

The leaves of this fast-growing tree are bipinnate. The leaves have serrated margins, and the tree branches have clusters of small golden-yellow flowers. Also present are numerous, pink/red, paper-thin parchment-thin (lantern like) seed pods (each pod containing two small black seeds). With ripening, these fragile pods lose most of their color, become brownish pink (see Figure 3) and eventually fall off the tree.

  Classification

Kingdom Plantar

Clades (4 of them)

Order Sapindales

Famly Sapindaceae

Genus Koelreuteria

Type species K. paniculata

The oldest know fossil of Koelreuteria (fruit valves) is from the Paleocene of southern Russia (Ablaev, 2000). Fossil fruits of this genus have also been found from middle Eocene deposits of the Green River Formation and Eocene deposits of British Columbia (see Wikipedia, 2025). Also found in the upper Eocene (about 34 million years old) Florissant Fossil Beds National Monument (see National Park Service Website nps.gov for some images of fossils (including a fossil plant from the Florissant Fossil Beds).

The species shown here is K. bipinnata. For images of the other two living species, see the website listed below.

Figure 1. Golden Tree in the process of shedding its "golden" pollen.

Figure 2. Seed pods (red color) of the Golden Tree.

Figure 3. Various parts of the Golden Tree: leaves, dried-out seed pods (in the previous figure these seed pods

were red, but a few months later = when this additional figure was taken, the red color had gone), and some  other small-red flowers still

attached to their thin stems.

References

Ablaev, A. G. 2000. Paleogene biostratigraphy of the coastal region in south Primorye. Vladivostok: Dal’nauka [in Russian].

https://www.youtube.com/watch?v=ttRU1-dlMR8

National Park Service Website   nps.gov

Wikipedia 2025

THE ALMOND TREE NUT

The almond tree (genus Prunus) is one of the earliest domesticated fruit trees. Based on molecular dating, it diverged apparently from the peach tree around 6 million years ago (= latest Miocene time). The earliest know fossilized almond tree remains are of Pleistocene age (17,000 to 14,000 years ago). Humans in the Near East/Himalaya Mountains have cultivated it (= genetic “engineering”) now for thousands of years. 

Almond trees are a type of drupe because the each fruit of an almond trees has a pit. Inside the pit, is a seed = the almond nut, which a person eats. Examples of other drupes are peaches, plums, cherries, walnut, and pecans. The "rule of thumb" is that if a plant produces a pit, then that plant is a drupe. 

The almond tree is closely related to the peach tree, and it is likely that almond trees originated by divergence peach trees. The blooms of the almond tree are white and pink.

The almond nut that is so popular today occurs on the tree Prunus amygdalus. It prefers a Mediterranean climate with a cool winter. California “fits that bill” perfectly. In fact, California produces 80% of the world’s almond supply. One fall-back, however, is that almond trees require lots of water. California now holds the world record for production of almonds.

  Classification

Kingdom Plantae

Clades 4 of them

Order Rosales

Family Rosaceae

Genus Prunus

Type Species P. amygdalus Batsch, 1801 [Linnaeus, 1753 was the first to name this tree, but in doing so, he created a “taxonomic tangle,” thus Batsch renamed this tree.

Note: (for those who are interested): the dietary evaluation of almond nuts (e.g. bought in a typical grocery store) have the following nutritional data: 

Saturated fat [1] 

Trans fat [0]

Polyunsaturated fat [4] 

Monounsaturated fat [10] = healthy fats that help lower bad cholesterol (LDL)

The three images shown below are all via: PublicDomain Pictures.net

Figure 1. Almond tree in bloom.

Figure 2 . Almond fruit split open to show a nut in its  pit.

Figure 3. Ready to eat almonds which have been extracted from their pits.

GRAY BIRD GRASSHOPPER

 Gray Bird Grasshopper Schistocerca niten

It is a large insect, up to three inches long. This insect is native to North America: especially California to Texas and Mexico. It lives in deserts, woodlands, and mountains, can  make powerful jumps that involve long-distance flight (several yards).

This kind of grasshopper is an omnivore, thus it eats vegetation (leaves, grasses, crops, fruits, vegetables) and small insects (e.g. aphids).

It can live year-around in some places (e.g., southern California---even in January).

Figures 1 and 2. Two Gray Bird grasshoppers (lengths about 3 inches) from Santa Clarita, southern California.

Reference. Wikipedia, 2026.

THREE UNUSUAL BIRDS

THE EMU

This animal is a large flightless bird endemic (native) to most of Australia (in fact, it is Australia’s largest native bird). This bird is the second tallest flightless bird in the world today. As a bipedal runner, it can sprint up to 30 miles per hour. It has a very powerful kick, enough to deliver serious blows! It is also an excellent swimmer.

Figure 1. An adult emu. Image from the Smithsonian Institution (open access).

This bird eats fruits, leaves, grasses, flowers, seeds, and insects; it especially likes grapes and dandelion greens. The emu lives throughout most (but not all) of Australia.

The adult female is up to 6 foot three inches tall, and it weighs up to 82 pounds, whereas the male weighs a maximum of 69 pounds. This bird has unique fluffy, double-shafted feathers. It also has powerful 3-toed legs that can run up to 30 mph and are also used to deliver serious blows when it is necessary to protect itself or its young. This bird has a throat pouch for producing deep drumming calls. It is the only bird with calf muscles.

CLASSIFICAN

Kingdom Animalia

Phylum Cordata

Class Aves

Order Casuariiformes

Family Casuariidae

Genus Dromaius

Type Species Dromaius novaehollandiae (Latham, 1790)

GEOLOGIC RANGE

They originated during the Late Oligocene or early/middle Miocene (about 25 to 15 million years ago) in Australia (Wikipedia, 2026). 

Fossilized eggshells of Dromaius, about 65,000 years old, are frequently found in Australia.

KIWI BIRD

The Kiwi is a flightless bird (with vestigial wing approximately the size of a chicken. Kiwis are included in a diverse group of flightless birds generally referred to as ratites (e.g., ostriches, cassowaries, emus, rheas, moa, and the extinct elephant bird). The Kiwi bird is the national symbol for New Zealand.

Figure 2. Kiwi bird (image via the Smithsonian Institution, open access).

The Kiwi, which is endemic to New Zealand, consists of five recognized species. In general, the kiwi birds are up to 18 inches tall and weight about 5 pounds. The eye relative to body mass of the kiwi is the smallest in all of the avian species.

Kiwi birds are most closely related to the extinct elephant bird of Madagasgar. 

Classification

Kingdom Animalia

Phylum Chordata

Class Aves

OrderApterygiformes

Family Apterygidae

Genus Apteryx

Type Species A. australis

The geologic time range of the kiwi is Miocene to Recent (Wikipedia, 2026).

Reference

Wikipedia, 2026

THE SANDILL CRANE

This bird used to be referred to as the “Grus Stork.” Today, there are six known subspecies of this bird. It lives today in North America (including Cuba) and also in northeast Siberia. It is a herbivore. The male weights up to 11 pounds and has a wingspan up to nearly 7 feet.

Figure 3. The Sandhill Crane, Image via the Smithsonian Institution (open access).

It has one of the longest fossil record of any extant bird: 10 million years [= late Miocene time] in Nebraska.

Classification

Kingdom Animalia

Phylum Chordata

Class Aves

Order Gruiformes

Family Gruidae

Genus Antigone

Type Species A. Canadensis (Linnaeus, 1758)

Reference:

Wikipedia, 2026.