DINOSAURS IN ANTARCTICA

Six genera are known: two are Early Jurassic age and four are Late Cretaceous age (Campanian Stage/Maastrichtian Stage). These genera are unique to Antarctica, but they are generally closely related to either South American dinosaurs.

When dinosaurs lived in Antarctica, the continent was ice free. During warm Early Jurassic time, all the continents on Earth were part of the single large continent called Pangea, which existed from the Late Paleozoic to the Triassic/early Jurassic time. Then the northern part of Pangea (Laurasia) separated and the central Atlantic Ocean simultaneously began to open up. The southern part of Pangea (Gondwana), which included South America, Africa, Arabia, Madagascar, India, New Zealand, Antarctica, and Australia, eventually underwent its own breakup, which occurred in stages. It started with Africa and South America separating from India, Antarctica, and Australia. During Cenozoic Paleogene time (66 to 23 mya), Antarctica became a separate continent. Its climate was mild until 34 mya (= end of the Eocene and beginning of the Oligocene), when continental glaciers began to accumulate in Antarctica.

                                        Figure 1. Pangea 

Figure 2. Breakup of Pangea, with Gondwana = all the

 southern continents.

By Middle Cretaceous times, dinosaurs in Antarctica were geographically somewhat isolated, but close connection between Antarctica and Australia still existed.

EARLY JURASSIC DINOSAURS

The two middle Early Jurassic (Pliensbachian Stage) [199–183 million years ago] dinosaurs found in Antarctica are the theropod Cryolophosaurus and the sauropod Glacialisaurus.

Their remains are both found at the same site in the Hanson Formation in the central part of the Transantartica Mountains that “divide” western from eastern Antarctica. This mountain chain was an active volcanic rift-system area.

Google-Earth image showing the location of the Hanson Formation in the Transantarctica Mountains.

 

Cryolophosaurus elliotti is based on a single specimen. It is the only theropod found so far in Antarctica. This dinosaur, which was an “apex predator” was 8 feet in height at the hips, 21 to 26 feet long, and it is estimated to have weighed 1000 pounds. It has an unusual-looking pompadour spanning its head from side to side. This dinosaur had primitive needle-like feathers.

Glacialisaurus hammeri is based on two specimens. This early sauropodomorph dinosaur was 20-25 feet long, and is estimated to have weighed approximately 5 tons. It had leaf-shaped teeth.

LATE CRETACEOUS DINOSAURS

Two of the four Late Cretaceous dinosaurs found in Antarctica are of Late Cretaceous age and have been reported as of Campanian Stage-age (79-77 mya). The other two dinosaurs have been reported as of Maastrichtian Stage-age (68 mya) age. All of their remains, however, are found at the same site in the Snow Hill Formation on Seymour Island, which is located just south of South America. These Snow Hill Formation dinosaurs are closely related to South American dinosaurs. 

Google-Earth image of the Late Cretaceous Snow Hill Formation dinosaur locale on Seymour Island.

Antarctopelta oliveroi is based on a single specimen of reportedly upper Campanian age. This ankylosaur was a herbivore with armor plates. This dinosaur is estimated as having been 13 feet (4 m) long.

Trinisaura is based on a single specimen of upper Campanian age. This ornithopod was 2.5 feet tall and 5 feet in length. 

Morrosaurus is based on a single specimen. This ornithopod was a herbivore elasmarian genus. Its geologic age has been reported as of Maastrichtian Stage (approximately 68 mya) of the Late Cretaceous  Period (approximately 68 mya). 

Imperobator is a paravian theropod (“an early bird”) that has been reportedly as of Maastrictian age. This dinosaur lacked an  enlarged sickle claw.

The biodiversity of Antarctican dinosaurs is very low, but this is to be expected because the continent is currently covered in glacial ice and the climate is not conducive to prospecting for fossils.

References Consulted:

wikipedia.org

MOUNT EREBUS, ANTARCTICA: THE WORLD’S SOUTHERMOST ACTIVE VOLCANO

This volcano is on Ross Island, near McMurdo Station (USA) and Scott Base (New Zealand). [Note: McMurdo Station sits on the mainland of the Antarctica continent]. Mount Erebus is the southernmost active volcano on Earth (at approximately 77.5°S, 167.1º E) and is one of the only few volcanoes that is consistently active. Ross Island also has three other volcanoes, but they are inactive. Mount Erebus was discovered in 1841 by the polar explorer Sir James Clark Ross. In Greek mythology, the father of Erebus was Chaos, and Erebus’ mother was Gaia (or Earth). Erebus was made of darkness, and he filled the corners of the world with darkness; thus, Erebus means a “dark region.”

Figure 1. Antarctica in relation to South America and Africa (a Google Earth image), and the location of Mount Erebus. 

Figure 2. Location of Mount Erebus on Ross Island.

Mount Erebus has been active for 1.3 million years. It is a polygenetic stratovolcano composed of anorthosite-porhyrite and tephrite phonolite. The bottom half is a shield volcano, whereas the upper half, whose slope dips approximately 30°, is a strato-volcano, with a lava lake in its inner summit crater. This lava (magma) lake is permanent, and there is continuous degassing (Wikipedia). Also, it spews out, on the average, 80 grams of gold a day, all of it is dissolved in the sulfurous volcanic gases (atlasobuscua.com/places/mt-erebus).

Figure 3. Side view of Mount Erebus, as seen from a tourist ship on the Ross Sea. You can readily see the dual-aspect of the shape of this volcano. 

Figure 4. Caldera (housing a lava lake) at the top of Mount Erebus. There are two inactive calderas on the flank of the active caldera.

Figure 5. NASA satellite image showing the glowing, active lava lake in the active caldera at the top of Mount Erebus.

There are fumarolic ice towers, up to 60 feet high, associated with this volcano, and they form around escaping gases on the surface of the volcano.

Figure 6. A fumarolic ice tower (a public domain image taken in 2010 by Peter Rejeck, National Science Foundation, see photolibrary, usap.gov). The original of this image is on the public domain website: atlasobscura.com/places/mt-erebus).

Additionally, there are dark ice caves associated with this volcano. They have relatively warm temperatures (a constant of 32°, making them likely to be home to extremeophile organisms (e.g., moss, algae, some arthropods, and some nematodes can live in these caves) (Wikipedia).

Websites Consulted

atlasobuscua.com/places/mt-erebus

coolantarctica.com

en.Wikipedia.org

photolibrary.usap.gov

THE TETHYAN CURRENT CONNECTION

The Late Cretaceous, Paleocene, and Eocene (see the time diagram shown below) world oceans were influenced by a warm  equatorial (tropical) current known as the Tethys Current, which flowed westward from the Tethys Sea in Asia and Western Europe and continued westward into southern Mexico and Central America. This current dispersed the larvae of marine mollusks and other biota into the west coast of North America, as far north as Washington. This dispersal coincided mainly with the early Eocene, the warmest time of the last 65 million years of Earth history.

The position of the Tethys Current is shown below. There was an open

seaway connection between the Atlantic and the Pacific oceans in the area now known as Central America and South America. Shallow-marine mollusks found in Eocene rocks show very strong affinities to their counterparts in the Gulf Coast of the United States and in Western Europe (i.e., southern England, France, and Italy). 

Since the 1920’s, in the Gulf Coast, and the 1930’s in California, invertebrate paleontologists studying large foraminifera, corals, mollusks, crabs, and echinoderms, have noted very similar looking species in these regions versus that of southern England and France. During the last 40 years, I have focused my own research largely on establishing the details of this influx of Western European thermophilic (warm water) genera and their related species into the west coast of the United States, especially into southern California.

By the means of detailed geologic mapping, extensive collecting, and analyses of the collected fossils, I and my students have been able to determine that the most extensive influx of mollusks from the Old World was during the warmest time of the Eocene; namely, the early Eocene [especially during an interval of geologic time known as the “Capay Stage,”] about 45 million years ago. This stage coincided with the Early Eocene Climate Optimum (= EECO). Subsequent tectonic activity displaced the rocks containing these fossils northward several hundred miles and also rotated some of the rocks nearly 90 degrees clockwise. This tectonic displacement was not recognized (by paleomagnetic studies) until the 1990’s.

Among the most famous of the mollusks that were introduced into are the gastropods Velates, Campanile, Gisortia, and Clavilithes. There are also many others, but these four genera are representative. At the end this post, I figure and discuss these genera. 

                                      

Reference:

Savazzi, E. 1992. Shell construction, life habits and evolution in the gastropod Velates. Palaeogeography, Palaeoclimatology, Palaeoecology 99:349-360. Costs $$ to view online.

Comparison Between Western Europe and California Eocene                      Gastropod Species: 

Velates perversus Paris Basin, France, two views: side and aperture.

Velates perversus Southern California, two views: side and aperture.

The name “Velates” is derived most likely from the word “velum,” which is a veil or membrane covering; sort of like a length of cloth attached to a hat, thus covering the neck and shoulders (like the extension of the helmet of the character "Darth Vader" in the “Starwars” movies). Adult Velates shells normally a lateral (sideways) sloping extension.

Velates belongs to family Neritidae, which most collectors refer to as nerites, whose living members (several hundred species) are small with brightly colored shells that can be found in trees, springs, rivers, swamps, marshes, and brackish water. Most species are found, however, in shallow-marine waters, especially along intertidal coastlines in tropical seas. 

Velates ranges in time from, possibly Late Cretaceous, but with certainty from Paleocene to Eocene in Europe, Africa, Asia, North America, and the Caribbean region. Velates is peculiar for nerites: it has the largest shells of any nerite (fossil or living), the aperture occupies about one-third of the base of the shell, with the rest consisting of a thick callus.

Their largest shells reached about 150 mm in diameter; making Velates the largest neritid. Its shell is unusual for a nerite because of its considerable thickness, especially on its ventral surface, where a broad thick callus (shell buildup) creates a very wide, smooth surface (pad). Whereas nearly all nerites are free to crawl around, it appears that Velates was rather comfortable in settling partially into the sediment substrate (i.e., the basal callus pad created an “anchor” of sorts). Thus, Velates might have been a partial burrower in soft-bottomed sediments. The thick callus would could have served as an “anchor.” Other evidence to support a burrowing lifestyle is that its outer surface of the shell is smooth and shiny and never show attached epibionts (unless they occurred post-mortem). There are only a few nerites that live today as infaunal soft-bottom dwellers, but these nerites are small in size.

 The Velates specimens that I and my students were fortunate to find and collect were present only in transgressive  (deepening upsection) facies in shallow-marine water environments near the bases of formations. They are not scattered throughout a formation which has different environments of deposition.

Gisorta tuberculosa, France, left image, apertural view.

Gisortia clarki, California, right image, apertural view.

Gisortia tuberculosa, France, left image, dorsal view.

Gisortia clarki from California, left image, dorsal view.

The size of this California specimen is length 12 cm. 

The genus Gisortia belongs to family Cypraeidae (i.e., popularly known as the cowries). The global geological time range of Gisortia is Late Cretaceous (Maastrichtian) to late Eocene, but on the west coast of North America this genus occurs only in lower Eocene (“Capay Stage”) strata in southern Baja California, Mexico and in southern and central California. Gisortia is a large-sized gastropod shallow-marine gastropod.

Clavilithes longaevus, France, left image: apertural view, 

right image: dorsal view.

Clavilithes tabulatus from California. Left image: apertural view, 

right image: dorsal view.

Clavilithes lived from Paleocene to Pliocene, with various species found in Africa, Asia, Europe (especially southernmost England and also the Paris Basin, France), North America, and South America. In California, it is restricted to the early Eocene and to the lower part of the middle Eocene. It is a very distinctive genus, with tabulate shells ± fine spiral ribs. Individuals can reach up to 85 mm in height and 35 mm in width.

Clavilithes giganteum Lamarck, left image, an incomplete specimen from middle Eocene deposits, Paris Basin, France. 

right image: Campanile dilloni from southern California: dorsal view, height 15.5 cm.

Campanile has a geologic range from Late Cretaceous (Maastrichtian) to recent. Today, it occurs only in the Perth area of southwestern Australia. On the Pacific coast of North America, it is found in Paleocene an Eocene deposits, in California and Baja California Sur, Mexico.

THE STRANGE OARFISH

Classification of the oarfish:

Phylum Chordata

Class Actinopterygii

Order Lampriformes

Family Regalecidae

Genus Regalecus

(Two) Species: glesne Ascaniusm 1772 and russelii (Cuvier, 1816)

Both species are circum-global, but only R. russelii has been found in California (Feeney and Lea, 2018).

The living oarfish is a ray-finned fish with a ribbon-like shape that can be up to 36 feet long (11 m). It has a circum-global distribution, except for polar regions. It is most commonly found in the tropics to middle latitudes. It lives at depths of 3,200 feet (1,000 m) but can occur in shallower water (nearshore to 200 m depths). It is rarely been seen in the vicinity of beaches, unless it has been washed up. In such cases, even in southern California, it creates great attention. Typically, in such cases, pictures will be taken with 15 or 20 people holding up a dead oarfish. 

This actual specimen of an oarfish (Regalecus sp.) is on display in an exhibit at the Natural History Museum of Los Angeles County (LACM). This specimen is 14.5 feet long. It was alive when it swam into Big Fisherman Cove at Catalina Island in 2006. Researchers photographed it as they swam aside it, before it died of natural causes. Image courtesy of Lindsey T. Groves, Collections Manager of Malacology at LACM. 

My sketch of a living oarfish.

In forklore, oarfish have been associated with “sea serpents” and forbearers of doomsday calamities (e.g., earthquakes and other catastrophic changes).

The oarfish body is narrow laterally, with a dorsal fin (typically reddish) along the entire length. It swims, in an undulating manner, by means of its dorsal fin, but it and can also swim in a vertical position. Its head is small with no teeth (it swallows small-sized marine crustaceans, called krill). Also the oarfish has no swim bladder. 

It has a small head with no teeth, but it eats krill. 

The ancestor of the extant giant oarfish might have been stickleback fish, which possibly date back to the Early Cretaceous (early Cenomanian Stage) in Italy (see (Sorbini, 1966). It is also interesting to note that stickleback fish today are confined to the Northern Hemisphere where they can live in oceans, brackish, or fresh water.

References Cited and/or used:

australian.museum

Feeney, R.F. and R.N. Lea. 2018. California records of the oarfish, Regalecus russelii (Cuvier, 1816) (Actinopterygii: Regalecidae). Bulletin of Southern California Academy of Sciences 117(3):169–179. (pdf available online, for free).

Sorbini, L. 1996. New superfamily and three new families of tetraodoniform fishes from the Upper Cretaceous: the earliest and most morphologically primitive Pectognatus. Smithsonian Contributions to Paleontology 82:1–59. (pdf available online, for free).

en.Wikipedia.org

KANGAROOS, WALLABIES, AND TREE KANGAROOS

Their higher classification is:

Class Mammalia

Infraclass Marsupialia (the pouched mammals)

Order Diprotodontia

 Family Macropodidae (macropods = kangaroos, wallabies,  

        and tree kangaroos) 

                    

There are several genera and many species within the macropods.

[note: The word macropod literally “means bigfoot.”]

KANGAROOS:

The word “kangaroo” is usually reserved for larger members of macropods. Kangaroos are also called “roos,” and their post-birth young, that live in the mothers’ pouch, are called “Joey’s.” 

The ancestors of kangaroos were tree-dwelling opossum-like animals that lived during middle Miocene time. These earliest species had tiny size, primitive features (probably quadrapedal, probably a bounding gait, and lived in rainforests). By late Miocene time, kangaroos appeared. They increased greatly in diversity during the much drier times during the Pliocene and early Pleistocene, and they eventually developed the true bipedal hop. 

The largest known kangaroo, Procoptodon golidath appeared during the Pleistocene. As shown in the figure below, it was a bipedal grazer, with a short face and a single functioning hind toe.

Procoptodon golidath, up to 6.5 feet tall and as much as 530 pounds. Image modified from Savage and Long (1986: p. 189).

Modern kangaroos have large, powerful hind legs, a long tail for balance, and a relatively small head. Today there are four living species of kangaroos assigned to genus Macropus. They include M. rufus (the "red" kangaroo); M. giganteus (the “eastern gray" kangaroo), M. fuliginosus (the “western gray” kangaroo), and M. antilopinus (the antilopine kangaroo [also gray in color].” For images of each of these species, see <worldatlas.com/articles/how-many-species-of-kangaroos-are there.html> 

Kangaroos live mostly on dry plains, where they eat grasses. Australian kangaroos are strict vegetarians. The larger species are the Australian equivalents of large browsing and grazing animals like antelope, buffalo, deer) found on other continents. 

 

Kangaroos have no lower canine their teeth, and upper canines are usually also absent. As a result of their diet, kangaroos have specialized molars, which are unusually curved and high-crowned. Their molars grind down fast (because of the hard silica content of the grass) and are unusual, in that they actually move forward before falling out and replaced by new teeth growing in the back of the jaws. This process is called polyphyodonty, and only occurs in hyraxes, elephants, manatees, and kangaroos!

“Western-gray kangaroo,” Yanchep National Park, north of the city of Perth (see the Google Image near the end of this blog post), in Western Australia. Image kindly donated by Matt Ventimiglia, 2023. This park is a bushland and wetland that harbors kangaroos and rich birdlife.

WALLABIES:

A wallabie is a small to medium-sized (less than 45 pounds) kangaroo, ranging from rabbit size to less than about 3 feet tall). Also compared to larger-sized kangaroos (which can weight up to 200 pounds and up to 8 feet tall), wallabies have much shorter legs and greater color variation in their fur. Wallabies are fast runners and can jump quite high. Their teeth are flatter with lower crowns than those of larger kangararoos.

There are several genera, and they live in the wild in Australia and New Guinea. 

A 13-pound “Yellow-footed Rock Wallaby,” living at the Living Zoo in Palm Desert, Riverside County, southern California. This animal belongs to genus Petrogale. Image courtesy of C. and K., 2023.

In the wild. in Queensland of South Australia, wallabies are considered as “near threatened.” Thus, zoos throughout the world are sheltering these animals in order to help preserve them. 

“TREE KANGAROOS”:

Tree-dwelling (aboreal) small-sized (up to 30 inches long and up to 20 pounds) kangaroos belonging to genus Dendrolagus live only in a small area in extreme northeastern Australia and in relatively large areas on an island comprised of both the countries of Papua and New Guinea, immediately north of Australia.

Google Earth image (2004). 

The common name “tree kangaroos” is commonly used for at least eight living species of them. They are slow-moving animals but are great leapers. They live in trees, mostly in the montane tropical-rain forests. They have very thick coats of fur, which can have multi-colored)  areas. They also have a sponge-like grip on their paws and soles of their feet. Their front and hind limbs are muscular with curved, long, and very sharp claws for climbing trees. Also, their hind feet have rather long pads. It is interesting that tree kangaroos never back down trees head first, unlike what opossums do. However, tree-kangaroos do not eat grass, instead their diet consists of berries, roots, and insects and other invertebrates (Lawlor, 1979). Most of the “Golden-mantled tree kangaroos” are the most threatened of all marsupials because of habitat destruction and uncontrolled hunting (Wikipedia, 2023). Dendrolagus has a geologic time range of Pliocene to recent (Prideaux and Warburton, 2023).

An example of a tree kangaroo: the Goodfellow’s tree kangaroo (Dendrolagus goodfellowi) (this sketch by the author was based on a Wikipedia, 2023) image). 

Modern-day tree kangaroosThey are about 16 pounds in weight and up to three feet long. They live in rainforests, from sea level to 10,000 feet in elevation, only on the island of New Guinea, just north of Australia. They live up to 23 years in captivity (Animal Diversity Website, 2023).

References Consulted:

Animaldiversity.org/accounts/Dendrolagus_goodfellowi/2023

en.Wikipedia. 2023.

Prideaux and Warburton. 2023. A review of the late Cenozoic genus Bohra (Diprotodontia: Macropodidae) and the evolution of tree-kangaroos. Zootaxa, June, 2023:1–95 (pdf not free).

 

Savage, A.J.G. and M.R. Long (1986). Mammal evolution. British Museum (Natural History), 259 pp. 

worldatlas.com/articles/how-many-species-of-kangaroos-are-there.