Woodward Original Early Drawing of Ordovician Marine

WOODWARD, Alice B. (1862–1951).
Ordovician Marine Life (Gastropod, Coral, Astylospongia, Trilobites, Calymene, Asaphus, Ceraurus, Crinoids, Polyzoan, Pterinaea, Graptolite, Cystid, Lampshell).
Original Illustration in pen, ink and grey wash, heightened in white.
c.1905-1912.
10 5/8" x 7 5/8" sheet.

Original artwork for Henry R. Knipe's "Evolution in the Past". Illustrated on page 22.

1. The first gastropods were exclusively marine, with the earliest representatives of the group appearing in the Late Cambrian (Chippewaella, Strepsodiscus), though their only gastropod character is a coiled shell, so they could lie in the stem lineage, if they are gastropods at all. As such, it's not until the Ordovician that the first crown-group members arise. By the Ordovician period the gastropods were a varied group present in a range of aquatic habitats.

2. Streptelasma, extinct genus of corals, existing as single animals rather than colonial forms and found as fossils in marine rocks of Ordovician to Devonian age (488 million to 359 million years old). Each horn-shaped specimen represents a single individual.

3. Astylospongia are a genus of small pear-shaped siliceous fossil sponges including important index fossils occurring in Middle Silurian strata.

4. Trilobites (meaning "three lobes") are a group of extinct marine artiopodan arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period (521 million years ago), and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 300 million years. Trinucleidae is a family of small to average size asaphid trilobites that first occurred at the start of the Ordovician and became extinct at the end of that period. It contains approximately 227 species divided over 51 genera in 5 subfamilies. The most conspicuous character is the wide perforated fringe of the head.

5. Calymene Brongniart, 1822, is a genus of trilobites in the order Phacopida, suborder Calymenina, that are found throughout North America, North Africa, and Europe in primarily Silurian outcrops. Calymene is closely related to Flexicalymene, and both genera are frequently found enrolled. Calymene trilobites are small, typically 2 cm in length. The cephalon is the widest part of the animal and the thorax usually has 13 segments.

6. Asaphus is a genus of trilobites that is known from the Lower (upper Arenig) and Middle Ordovician of northwestern Europe (Sweden, Estonia, Saint Petersburg Area).

7. Ceraurus is a genus of cheirurid trilobite of the middle and, much more rarely, the upper Ordovician. They are commonly found in strata of the lower Great Lakes region. These trilobites have eleven thoracic segments, a very small pygidium and long genal and pygidial spines. Ceraurus is quite common in the Ordovician of upstate New York, south-central and south-eastern Ontario, and the St. Lawrence Valley in Quebec, as well as in the Canadian Arctic. It and similar genera range in size from less than quarter an inch to well over five inches. Similar genera of trilobites occur in the Ordovician outcrops of the Volkhov River, near St. Petersburg, Russia.

8. Crinoids are marine animals that make up the class Crinoidea, one of the classes of the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. Glyptocrinus is an extinct genus of sea lily that lived from the Middle Ordovician to the Early Silurian (471.8 - 436.0 Ma). Its remains have been found in North America.

9. Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about 0.5 millimeters (1⁄64 inch) long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The terms "Polyzoa" and "Bryozoa" were introduced a year apart, in 1830 and 1831 respectively. Soon after it was named, another group of animals was discovered whose filtering mechanism looked similar, so it was included in Bryozoa until 1869, when the two groups were noted to be very different internally. The new group was given the name "Entoprocta", while the original Bryozoa were called "Ectoprocta". Disagreements about terminology persisted well into the 20th Century, but "Bryozoa" is now the generally accepted term.

10. The name graptolite comes from the Greek graptos meaning "written", and lithos meaning "rock", as many graptolite fossils resemble hieroglyphs written on the rock. Linnaeus originally regarded them as 'pictures resembling fossils' rather than true fossils, though later workers supposed them to be related to the hydrozoans; now they are widely recognized as hemichordates.

12. Cystidea are an order of Crinoidea, mostly fossils of the Paleozoic rocks. They were usually roundish or egg-shaped, and often unsymmetrical; some were sessile, others had short stems.

13. Lampshell Platystrophia is an extinct genus of brachiopods that lived from the Ordovician to the Silurian in Asia, Europe, North America, and South America. It has a prominent sulcus and fold. It usually lived in marine lime mud and sands.