Mastodon

Molars of Mammut americanum, Oklahoma.

Related to elephants and extinct for close to 11,000 years, mastodons were one of the megafauna that once inhabited North America. They were similar to modern elephants with large, curved tusks and corrugated grinding surfaces of the teeth, but they were also similar to mammoths with their shaggy hair. Remains of mastodons were first discovered in 1705 when a tenant farmer discovered a five-pound tooth. More teeth were discovered in other parts of North America until a French anatomist finally gave mastodons a name. The common name was based on the teeth as the conical cusps resembled breasts: mastos (Greek for breast) and odont (for tooth). Although the shape of the tooth first gave thought to flesh-eating beasts, it has since been concluded that the shape of the teeth provided best for browsing and grazing.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.

Sharks

Fossilized Shark Tooth

Sharks have been in existence since at least the Ordovician Period over 450 million years ago. This was during the time of vast marine diversity, and little diversity present on land. One of the earliest representations of sharks discovered was Cladoselache, which differs in form from modern sharks, but was still a high-speed predator. The most common discovery related to ancient sharks are their fossilized teeth. As sharks shed thousands of teeth throughout their lifespan, there is a higher chance for one of these teeth to find the right conditions for fossilization; however this often presents a problem of identification. In addition to scattered and mixed teeth findings, many sharks exhibit dignathic heterodonty, or a difference in the upper and lower teeth in addition to parasymphyseal, or a difference in teeth in relation to jaw position. Gender difference are also often translated to the teeth making it hard to identify the species a shark tooth originated from.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.

Lynx Spiders

Lynx Spider, Oxyopes acleistus

Lynx spiders of the family Oxyopidae are found throughout the world, particularly in the tropics and subtropics. These spiders are active, roving hunters often using foliage for camouflage to ambush prey. Some species can jump up to 2 cm (.79 in) in the air to catch insects in flight. Although lynx spiders usually do not build webs, there are exceptions. These spiders are also very protective of their eggs, and often die of starvation due to this behavior.

Cottontail Rabbit

Camouflaged Eastern Cottontail, Sylvilagus floridanus

The cottontail rabbit is a genus of rabbits, Sylvilagus, with sixteen species. The most commonly spotted, and the one with the widest distribution, is the Eastern Cottontail. Although coloration may vary between species, all have the distinct "cotton ball" tail. These animals can live in a wide variety of habitats and eat a wide variety of foods. They mainly feast on grasses and herbs, but often find their way to gardens. Rabbits may breed up to four times a year, and babies are on their own in three to four weeks. It is important to note that the mother rarely stays with her young, but that does not mean she has abandoned them.

A short break from fossils due to a busy week, but they will return next week!

Sea Urchins

Extinct Sea Urchin, Sinaecidaris tauozensis [Taouz, Morocco]

Sea Urchins, of the class Echinoidea, are a type of echinoderm, much like brittle stars and jimbacrinus. Echinoderms, of the phylum Echinodermata, existed Precambrian over 600 million years ago. They have only been found in marine waters with 6,000 species still in existence. They are characterized by a well-developed water vascular system and by their mesodermal skeleton.

Extinct Pencil Urchin, Acrocidaris nobilis [Jurassic Period/LaRochelle, France]

Of the thousands of species of echinoderms, only about 700 species are sea urchins. As with most within the phylum Echinodermata, adult sea urchins have a fivefold symmetry called pentameral. They have characteristic long spines and a spherical shape. These spines serve not only as protection, but also as a way to move and a habitat for other creatures such as fish. Sea urchins feed on organic matter with one of their primary food sources being seaweed.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.

Brittle Star

Brittle Star, Ophiura graysonensis [Del Rio Formation/Lake Waco Spillway/McLennan County, TX]

The class Ophiuroids is a large group of echinoderms which include the basket stars, Euryalida, and the more familiar brittle stars, Ophiurida. Although similar in appearance, they are not related to starfish which belong to the class Asteroidea. The brittle star has a central, disk-shaped body with long, flexible arms. In order to move, the brittle star wriggles its arms resulting in gliding movement reminiscent of snakes. As the common name implies, brittle stars are fragile, but can replace lost limbs. Although early members of Ophiuroids appeared during the Ordovician Period 500 million years ago, the still extant genus Ophiura is of the more recent Cretaceous Period 145 million years ago. Whole fossils of brittle stars are rare as they rapid fall to pieces after death due to their fragile nature.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.

Jimbacrinus

Crinoid, Jimbacrinus bostocki

Jimbacrinus, nicknamed feather star, belong to the order Cladida, long since extinct. These marine creatures were a type of crinoid, a class that is characterized by a fivefold symmetry and often confused for plants. While few crinoids exist in the present-day, they were once found found in larger numbers during the Paleozoic Era, particularly during the Permian Period. An abundance of fossils of Jimbacrinus are found in Western Australia where some species once grew up to 25 cm (10 in) tall. This specific genus lived solely in what is now Australia, but other fossils from the extinct family Calceolispongiidae have also been found in the United States and India in addition to Australia.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.

Trilobites

Trilobite, Asaphiscus wheeleri [Wheeler Shale/Middle Cambrian]

Trilobites are an extinct class of arthropods defined by distinctive three-lobed, three-segmented forms. Evidence of their existence dates back to the beginning of the Cambrian Period 542 million years ago. They dominated the seas until their extinction during the Great Dying, the most severe extinction event which occurred between the Triassic and Permian Period 251.4 million years ago. Fossils of these creatures have been found on every continent, with areas such as the Wheeler Shale in Utah, the Emu Bay Shale in Australia, the Burgess Shale in British Columbia, and the Chengjaing Formation in China as being notable locations to find trilobites. They ranged in size from 1 cm to 70 cm (28 in), had a flower-like eye, and a thick chitinous exoskeleton which was shed often. There are currently over 20,000 recognized species of trilobites organized into 10 different orders.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.

Ammonites

Pervinquieria trinodosa, Duck Creek, Bryan, Oklahoma

Ammonites are of the extinct marine invertebrates of the subclass Ammonoidea within the class Cephalopoda. The name ammonite arose in 79 AD from Pliny the Elder. It is derived from the Egyptian god Ammon and the symbolic rams horns in his depictions. As seen in all fossils, ammonites are recognized for their spiral shape shells although there is variation between species.

Ammonite, Unknown

These predatory creatures lived in a shell that were constantly built as they grew. The size varied with fossils of many found to be over 1 m (3 ft) in diameter. Their tentacles extended from the shell to snare prey. A sharp, beak-like jaw awaited in the middle of the tentacles. Although not closely related, they moved like modern-day nautilus. Chambers within the shell were full of either fluid or gas and allowed movement within the water column. They also had a method of jet propulsion through a funnel opening within the shell for more precise horizontal movement.

Unknown, Arcadia Park Shale, West Dallas, Texas

Ammonites first appeared and evolved during the Devonian Period of the Paleozoic Era 419.2 million years ago, and they existed until the end of the Cretaceous Period of the Mesozoic Era 66.0 million years ago, disappearing with the dinosaurs. Fossils of these creatures play an important role as size, shape, and shells of ammonites can be used to date geological layers. The septa, or dividing walls of the shell, can be used to classify order, and therefore time period, of the specimen.

From the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary.