biology

Wessiea

Wessiea is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Wessiea rather than just read about it. In short: Wessiea is an extinct morphogenus of fern not placed in a specific family. Wessiea is known from Late Cretaceous and Middle Miocene age fossils found in Central Washington USA and Southern Alberta Canada.

Key takeaways

Wessiea belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Wessiea to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Wessiea from memory before moving on to harder problems.

Reference excerpt

Wessiea is an extinct morphogenus of fern not placed in a specific family. Wessiea is known from Late Cretaceous and Middle Miocene age fossils found in Central Washington USA and Southern Alberta Canada. Two species are described in the morphogenus, W. oroszii and the type species W. yakimaensis.

History and classification The genus was first described from specimens of silicified rhizomes and frond bases in blocks of chert. The chert was recovered from the "Ho ho" site, one of the "county line hole" fossil localities north of Interstate 82 in Yakima County, Washington. The "Ho ho" site works strata which is part of the Museum Flow Package within the interbeds of the Sentinel Bluffs Unit of the central Columbia Plateau N2 Grande Ronde Basalt, Columbia River Basalt Group. The Museum Flow Package interbeds, designated the type locality, are dated to the middle Miocene and are approximately 15.6 million years old. The holotype specimen, rhizomes and fronds #1–3 and 3 E2 #1–3, are preserved in chert block 3A1 and housed in the Burke Museum of Natural History and Culture as specimen number "UWBM 56441". The paratype, number 3F1 #2 top on specimen "UWBM 56441", is a rhizome which shows root gaps, roots and frond bases. The specimens of chert were studied by paleobotanists Kathleen B. Pigg of Arizona State University and Gar W. Rothwell of Ohio University. Pigg and Rothwell published their 2001 type description for Wessiea yakimaensis in the American Journal of Botany. In their type description they note the etymology for the generic name is in honor of Wesley C. Wehr for his numerous contributions to Tertiary paleobotany of western North America. The specific epithet yakimaensis, is a reference to the type locality in the Yakima Canyon. Pigg and Rothwell noted the similarity between Wessiea and both the modern genus Diplazium and the fossil genus Makotopteris. The second species is known from ironstones of the Campanian age Horseshoe Canyon Formation, Alberta, recovered at the "Fred's site" locality. The fossils, housed in the Royal Tyrrell Museum of Palaeontology, were dissolved from the ironstone and embedded into a bioplastic for study. After embedding, the fossils were acid peeled by paleobotanists Rudolph Serbet and Gar W. Rothwell for study in thin section slides. Serbert and Rothell published the description of W. oroszii in a 2006 article. The specific epithet "oroszii" is a patronym honoring s Alfred Orosz, paleontologist for the Royal Tyrrell Museum, and discoverer of the species type locality.

Description The morphogenus is defined by the rhizomes and attached frond bases preserved by permineralization. The stipe shows the presence of two hippocampiform vascular bundles and the dictyostele is composed of forking meristeles.

W. oroszii The rhizomes of W. oroszii are erect in positioning and grow up to 7 mm (0.28 in) in diameter, larger than W. yakimaensis. The dictyostele is made of five to seven oval meristeles and has a maximum diameter of 2.8 mm (0.11 in). The frond bases are flattened on the upper sides and generally produced by the rhizomes in groups of two to four in a helical arrangement.

W. yakimaensis W. yakimaensis possesses rhizomes which are 1.5–3 mm (0.059–0.118 in) in diameter. The frond bases where preserved in the chert are in a distinct helical arrangement and diverge from the center of the arrangement in a recumbent positioning. The dictyostele is composed of four to five individual meristeles each being oval in outline. It is found in the chert blocks intertwined with the extinct Osmunda wehrii and anatomically preserved Anchistea virginica, which still lives in the forests of eastern coastal North America.

References

Worked examples

Example 1 — a first encounter with Wessiea

Start with the simplest possible case. Write down what Wessiea claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Wessiea before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Wessiea ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Wessiea

In research: Wessiea appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Wessiea in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Wessiea is common in secondary-school and first-year university syllabi. It links to neighbouring topics Campanian genus first appearances, Extinct flora of North America, Flora of the West Coast of the United States, so understanding it makes those chapters shorter.
In everyday life: Look for Wessiea outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Wessiea in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Wessiea means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Wessiea out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Wessiea in simple terms?

Why does Wessiea matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Wessiea?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Wessiea.