science

Stenophlebiidae

Stenophlebiidae is a science 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 Stenophlebiidae rather than just read about it. In short: The Stenophlebiidae is an extinct family of medium-sized to large fossil odonates from the Upper Jurassic and Cretaceous period that belongs to the damsel-dragonfly grade ("anisozygopteres") within the stem group of Anisoptera. They are characterized by their long and slender wings, and the transverse shape of the discoidal triangles in their wing venation.

Key takeaways

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

Reference excerpt

The Stenophlebiidae is an extinct family of medium-sized to large fossil odonates from the Upper Jurassic and Cretaceous period that belongs to the damsel-dragonfly grade ("anisozygopteres") within the stem group of Anisoptera. They are characterized by their long and slender wings, and the transverse shape of the discoidal triangles in their wing venation.

Description

Adult

Body

The head is similar to that of Recent Gomphidae with two large and globular compound eyes that are distinctly separated. The three ocelli are arranged in a triangle on the globular vertex. The mandibles are strong. The legs have short and strong spines.

Wings and wing venation

The largest species Stenophlebia amphitrite reached a wingspan of about 17.3 centimetres (6.8 in), while the smallest species Hispanostenophlebia barremiana reached only a wingspan of about 7.7 centimetres (3.0 in). Stenophlebiidae are distinguished by the following set of eight derived wing characters (synapomorphies): (1) a long not zigzagged secondary longitudinal convex vein in the postdiscoidal area, parallel to MP, the base of this vein being just distal of the discoidal triangle; (2) Cr long or very long, covering more than one or two cells between RA and RP; (3) pterostigma shifted basally; (4) pterostigma very long; (5) hindwing subdiscoidal space transverse and crossed by two veins or more; (6) the four wings elongate and more or less falcate; (7) forewing discoidal triangle long transverse; (8) numerous and well defined straight intercalary secondary longitudinal veins reaching posterior wing margin. Furthermore they share the following four synapomorphies with Prostenophlebiidae in the superfamily Stenophlebioidea: (1) a long and not zigzagged (or slightly zigzagged) secondary longitudinal convex vein in postdiscoidal area, parallel to MP, the base of this vein being about two or three cells or just distal of discoidal triangle; (2) a long and not zigzagged concave Mspl; (3) oblique vein "O" absent; (4) wings elongate. And they share these four synapomorphies with Prostenophlebiidae and Liassostenophlebiidae in the suborder Stenophlebioptera: (1) nodal crossvein Cr very oblique, i.e. angle Cr-RA > 140°; (2) subnodus Sn very oblique, with or without cross-veins reaching it; (3) CuAa with a broad area between the two most distal posterior branches; (4) presence of straight supplementary longitudinal veins in the areas between IR2 and MP near posterior wing margin.

Sexual dimorphism

Males are distinguished by a weak anal angle of the hindwing base and in some species of Upper Jurassic Stenophlebia by a club-like dilation of the terminal part of the abdomen. The male secondary genitalia are unknown, but probably were of the anisopterid type. The male terminalia of the abdomen are of the anisopterid type, thus composed of a pair of dorsal claspers (cerci) and an unpaired ventral process (epiproct). Nel et al. (1993) stated that the female ovipositor is reduced, while Bechly (2007, 2010) could demonstrate that at least the female of the stenophlebiid genus Cratostenophlebia had a distinct endophytic ovipositor.

Larva Fossil larvae of this extinct family have not been formally described yet, but Bechly (2007) suggested that the Nothomacromia larvae from the Lower Cretaceous Crato Formation of Brazil may be the larvae of Cratostenophlebia.

Classification The family group taxon was established by Needham (1903) as subfamily Stenophlebinae (sic) of the extinct damsel-dragonfly family Heterophlebiidae. It was emended and elevated to family rank Stenophlebiidae by Handlirsch (1906). Stenophlebia Hagen, 1866 is the type genus of this family. The species Sinostenophlebia zhanjiakouensis was originally assigned to the family Stenophlebiidae; however, the position and status of this species is very uncertain due to the poor preservation and insufficient original description. Zheng et al. (2016) transferred this species to the family Aeschnidiidae, and considered the genus Sinostenophlebia to be a likely junior synonym of the genus Leptaeschnidium. Bechly (2005) could show that the very small species "Stenophlebia" casta from the Upper Jurassic Solnhofen Plattenkalk of Germany is not related to Stenophlebiidae. It is now classified as Parastenophlebia casta in a separate family Parastenophlebiidae that belongs to the extinct damsel-dragonfly suborder Heterophlebioptera.

The family contains 9 described genera with a total of 18 species:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Stenophlebiidae

Start with the simplest possible case. Write down what Stenophlebiidae claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Stenophlebiidae 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 Stenophlebiidae 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 Stenophlebiidae

In research: Stenophlebiidae appears in science 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 Stenophlebiidae 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: Stenophlebiidae is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cenomanian extinctions, Cretaceous insects, Fossil odonates, so understanding it makes those chapters shorter.
In everyday life: Look for Stenophlebiidae 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 Stenophlebiidae in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Stenophlebiidae 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 Stenophlebiidae out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Stenophlebiidae in simple terms?

Why does Stenophlebiidae matter?

Because it connects several science 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 Stenophlebiidae?

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 Stenophlebiidae.