ammonoid: meaning, definition, pronunciation and examples
C2Academic/Technical
Quick answer
What does “ammonoid” mean?
An extinct marine cephalopod mollusc with a flat-coiled spiral shell, typically fossilised.
Audio
Pronunciation
Definition
Meaning and Definition
An extinct marine cephalopod mollusc with a flat-coiled spiral shell, typically fossilised.
A member of the scientific subclass Ammonoidea, important in paleontology as index fossils for dating rock layers.
Dialectal Variation
British vs American Usage
Differences
No significant spelling or usage differences. Both varieties use the term identically in technical contexts.
Connotations
Identical; purely scientific/technical.
Frequency
Used exclusively in paleontological, geological, and related academic fields in both varieties.
Grammar
How to Use “ammonoid” in a Sentence
[the] ammonoid [genus/species][study/collect] ammonoids[fossil/remains] of ammonoidsVocabulary
Collocations
Examples
Examples of “ammonoid” in a Sentence
adjective
British English
- The ammonoid suture pattern is complex.
- Ammonoid fossils are abundant in this layer.
American English
- The ammonoid fossil record is extensive.
- Ammonoid morphology varies widely.
Usage
Meaning in Context
Business
Not used in business contexts.
Academic
Common in paleontology, geology, and evolutionary biology texts and discussions.
Everyday
Virtually never used in everyday conversation.
Technical
Core term in paleontological classification and fossil identification.
Vocabulary
Synonyms of “ammonoid”
Neutral
Weak
Vocabulary
Antonyms of “ammonoid”
Watch out
Common Mistakes When Using “ammonoid”
- Misspelling as 'amonoid' or 'ammoniod'.
- Confusing with 'ammonite' (a specific type within Ammonoidea).
- Pronouncing as /əˈmoʊnɔɪd/ instead of /ˈæmənɔɪd/.
FAQ
Frequently Asked Questions
Ammonite is a common term often used for the whole group, but scientifically, Ammonoidea (ammonoids) is the subclass, and Ammonitida (ammonites) is one order within it. In casual use, they are often synonymous.
No. While both have coiled shells, ammonoids are cephalopods (related to squid and octopuses), not gastropods (snails). The shell structure and internal anatomy are fundamentally different.
They are excellent index fossils. Their rapid evolution, global distribution, and presence in specific rock layers allow geologists and paleontologists to date sedimentary rocks accurately and correlate strata across different regions.
Almost all ammonoids became extinct at the Cretaceous–Paleogene (K–Pg) extinction event, approximately 66 million years ago, along with the non-avian dinosaurs.
An extinct marine cephalopod mollusc with a flat-coiled spiral shell, typically fossilised.
Ammonoid is usually academic/technical in register.
Ammonoid: in British English it is pronounced /ˈæmənɔɪd/, and in American English it is pronounced /ˈæməˌnɔɪd/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Think: Ammonoid = Ammon + -oid (like or resembling). 'Ammon' from the Egyptian god Ammon (ram-horned) + '-oid' meaning resembling. Resembles the ram's horns of the god Ammon.
Conceptual Metaphor
TIME AS A LAYER: Ammonoids are 'markers' in the 'book' of geological strata.
Practice
Quiz
Ammonoids are most closely related to which modern animals?