Necromantis

Key takeaways

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

Reference excerpt

Necromantis is an extinct genus of bat that lived during the Eocene. Its fossils are found in the Quercy Phosphorites Formation of France and the Djebel Chambi in Tunisia. Specimens of Necromantis are notable for their large size and specialization towards a predatory lifestyle.

History The type species, N. adichaster, was first described by A. Weithofer in 1887 on the basis of fragmentary fossils from the Eocene deposits of the Quercy Phosphorites Formation. Weithofer did not designate a type specimen, simply describing a lower jaw. This material was later described in more detail by Pierre Revilliod in 1920, offering the holotype the number QW627. He described additional material, and classified it within five species: N. adichaster, N. gezei, N. marandati, N. planifrons and N. grandis. More recently, E. Maitre has described the fossils in more detail. N. grandis and N. planifrons have been considered indistinguishable from N. adichaster, but N. gezei and N. marandati may be distinct enough to retain their respective statuses as distinct species. Several indeterminate bat fossils in France may belong to Necromantis. Currently, only jaws and skulls are known, with a single humerus known as a postcranial remain. More recently, Necromantis fragmentatum has been found in the Late Eocene deposits of Djebel Chambi, Tunisia. This north African species is known from several isolated teeth.

Description

Necromantis adichaster has a skull length of about 32 mm and an estimated weight of 47 g, making it one of the largest bats in the Quercy Formation. Due to the lack of postcranial remains aside from a humerus, its exact wingspan is unclear. The other two species are smaller and possess several differences in regards to the trigon and cingulum. As noted by most researchers, Necromantis is unique among extinct and extant bats due to the sheer robustness of its jaws and skull. Its jaws are rather short and broad, bearing proportionally large teeth. The mandible is deep and thick and bears deep fossae; combined with the presence of a wide zygoma and a high-positioned condyle, it suggests that Necromantis had large, well developed masseters. The teeth themselves are strongly convergent with those of carnivoran mammals, bearing carnassial-like M1 and M2. The sagittal crest was tall, though less so than some other carnivorous bats like Vampyrum spectrum or Macroderma gigas.

Biology Necromantis has a strong negative tilting of the head, a characteristic thought to correlate with nasal-emission echolocation in bats, as seen in forms like megadermatids and phyllostomids, though it is not clear if Necromantis had a nose-leaf, too. Its powerful jaws, combined with the specialised dentition, strongly suggest that Necromantis was a carnivore, feeding primarily on other vertebrates. The shearing teeth and strong masseters suggest that it was more specialised to grind and crush flesh and bone than were other bat species. In particular, the angular process of the dentary implies that crushing force was much more important than the width of gape, unlike modern predatory bats. Due to its large eyes and expanded petrosals, Necromantis might have hunted like modern megadermatids and phyllostomids, relying on low frequency-echolocation and passive listening. Such bats inspect their surroundings from a perch, locate vertebrate prey like birds and mammals visually and by sound, and ambush it, killing it by biting at the back of the head.

Evolution and phylogeny Currently, Necromantis is placed in the family Necromantidae, along with the extinct genus Cryptobune, but their position relative to other bat families remains uncertain. Weithofer originally classified Necromantis as a megadermatid, and Revilliod later as a phyllostomid, but similarities to either clade were ultimately deemed to be inconclusive and likely derived from convergent evolution. More recently, a relationship with emballonurid bats has been proposed, possibly as a basal member descended from the early Eocene radiation of this clade, but currently this is inconclusive as well. Most recently, Necromantidae has been recovered as an early diverging lineage of stem bats.

Ecology Necromantis occurs in the Quercy Formation deposits estimated to date from the Middle to Late Eocene, 44-36 million years ago. The regional climate is thought to have been tropical in nature, marked by dense rainforests. Much like modern equatorial forests, the Quercy Formation bears a massive diversity of bat species; though the overall diversity of the region is thought to be incomplete, there are representatives of the still-extant Vespertilionidae, Molossidae, Hipposideridae and Emballonuridae (the former three still occur in Europe), as well as the now extinct Palaeochiropterygidae and Mixopterygidae.

References

Illustrations

Worked examples

Example 1 — a first encounter with Necromantis

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

In research: Necromantis 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 Necromantis 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: Necromantis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Enigmatic mammal taxa, Eocene bats, Eocene mammals of Africa, so understanding it makes those chapters shorter.
In everyday life: Look for Necromantis 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.

How to study Necromantis in 20 minutes

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

Frequently asked questions

What is Necromantis in simple terms?

Necromantis is an extinct genus of bat that lived during the Eocene. Its fossils are found in the Quercy Phosphorites Formation of France and the Djebel Chambi in Tunisia.

Why does Necromantis 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 Necromantis?

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 Necromantis.