science

Leptictida

Leptictida 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 Leptictida rather than just read about it. In short: Leptictida (leptos iktis "small/slender weasel") is a possibly paraphyletic extinct order of eutherian mammals. Their classification is contentious: according to cladistic studies, they may be (distantly) related to Euarchontoglires (rodents, primates and their relatives), although they are more recently regarded as the first branch to split from basal eutherians.

Key takeaways

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

Reference excerpt

Leptictida (leptos iktis "small/slender weasel") is a possibly paraphyletic extinct order of eutherian mammals. Their classification is contentious: according to cladistic studies, they may be (distantly) related to Euarchontoglires (rodents, primates and their relatives), although they are more recently regarded as the first branch to split from basal eutherians. One recent large-scale cladistic analysis of eutherian mammals favored lepictidans as close to the placental crown-clade; and several other recent analyses that included data from Cretaceous non-eutherian mammals found Leptictis to belong to the superorder Afrotheria. The most recent phylogenetic studies recover it as actually a paraphyletic assemblage leading to Placentalia.

Description The leptictids are a characteristic example of the non-specialized placental mammals that took part in the late Cretaceous-Paleocene evolutionary radiation, originally bunched together in the order Insectivora. The leptictids became extinct during the Oligocene. Their archaic cranium and dentition make it difficult to determine their relationship to other groups. Leptictid postcranial anatomy has been studied from the well-preserved middle Eocene Leptictidium specimens found at Messel, Germany. Judging from these specimens, lepticids were small placentals with a body length ranging from 60 to 90 cm (24 to 35 in). The head had a long and slender snout, probably featuring a short trunk, which may have been used for scratching the undergrowth in search of insects and worms. The mouth's archaic dentition included two or three incisors, a canine, and V-shaped cheek-teeth - four premolars and three molars. Their forelegs were shortened, but their hind legs were elongated. While this anatomy is reminiscent of small kangaroos and jerboas, suggesting a jumping locomotion, the structure of the tarsal bones hints at a specialization for terrestrial running. Perhaps these animals were capable of both modes of locomotion; running slowly in search for food, and jumping quickly to avoid threats. Additionally, the Messel specimens feature a surprisingly long tail, unique among modern placental mammals, formed by 40 vertebrae and probably used for balance.

Classification Order Leptictida Family Gypsonictopidae Genus Gypsonictops Genus Sikuomys Family Leptictidae Genus Amphigyion Genus Gallolestes Genus Labes Genus Lainodon Genus Palaeictops Genus Praolestes Genus Wania Subfamily Leptictinae Genus Blacktops Genus Ictopidium Genus Leptictis Genus Ongghonia Genus Prodiacodon Genus Protictops Family Pseudorhyncocyonidae Genus Diaphyodectes Genus Leptictidium Genus Phakodon Genus Pseudorhyncocyon

Notes

References Agustí, Jordi; Antón, Mauricio (2002). Mammoths, Sabertooths, and Hominids: 65 Millions Years of Mammalian Evolution in Europe. New York: Columbia University Press. ISBN 978-0-231-11640-4. OCLC 51534272.

Further reading Meehan, T. J.; Martin, Larry D. (2010). "New leptictids (Mammalia: Insectivora) from the Early Oligocene of Nebraska, USA". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 256 (1): 99–107. doi:10.1127/0077-7749/2010/0035. Novacek, Michael J (1977). "A review of Paleocene and Eocene Leptictidae (Eutheria, Mammalia) from North America" (PDF). PaleoBios. 1: 24.

External links Insectivore-like mammals: Tiny teeth and their enigmatic owners

Illustrations

Worked examples

Example 1 — a first encounter with Leptictida

Start with the simplest possible case. Write down what Leptictida 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 Leptictida 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 Leptictida 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 Leptictida

In research: Leptictida 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 Leptictida 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: Leptictida is common in secondary-school and first-year university syllabi. It links to neighbouring topics Eocene mammals, Late Cretaceous first appearances, Leptictida, so understanding it makes those chapters shorter.
In everyday life: Look for Leptictida 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 Leptictida in 20 minutes

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

Frequently asked questions

What is Leptictida in simple terms?

Why does Leptictida 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 Leptictida?

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 Leptictida.