# Arundelconodon

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Arundelconodon
> Markdown URL: https://mediated.wiki/source/Arundelconodon.md
> Source: https://en.wikipedia.org/wiki/Arundelconodon
> Source revision: 1354692969
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

***Arundelconodon*** is an extinct [genus](/source/Genus) of [mammal](/source/Mammal) of the family [Triconodontidae](/source/Triconodontidae), containing the species ***Arundelconodon hottoni***. It is known from multiple dental remains from the [Arundel Clay](/source/Arundel_Clay) in Maryland, United States, dated to the [Early Cretaceous](/source/Early_Cretaceous). The remains consist [jawbone](/source/Jawbone) fragments with [premolar](/source/Premolar), [molar](/source/Molar_(tooth)), and [canine teeth](/source/Canine_teeth). Its anatomic features are intermediate between [Jurassic](/source/Jurassic) and later [Cretaceous](/source/Cretaceous) triconodonts. The deposits from which it is known represent either a fringe swamp or a [floodplain](/source/Floodplain), likely near a coast.

## Discovery and naming

The [type specimen](/source/Type_specimen) of the [genus](/source/Genus) *Arundelconodon* was [described](/source/Species_description) by paleontologist Richard L. Cifelli and colleagues in 1999. The [type species](/source/Type_species) was named *Arundelcodon hottoni*. Their description was based on a "remarkably complete" jaw from the [Arundel Clay](/source/Arundel_Clay) of Maryland, United States. The genus name comes from the words *Arundel*, in reference to the Arundel Clay where the remains were found (itself named after [Anne Arundel County, Maryland](/source/Anne_Arundel_County,_Maryland),[1] named in honor of [Anne Arundell](/source/Anne_Arundell), wife of the first [proprietor](/source/Proprietary_colony) of Maryland, [Cecil Calvert](/source/Cecil_Calvert,_2nd_Baron_Baltimore)[2]), and *conodon*, which is Greek for "cone-tooth". The [specific name](/source/Specific_name_(zoology)), *hottoni*, was given in recognition of the contributions of [Nicholas Hotton](/source/Nicholas_Hotton) to vertebrate paleontology.[3] In 2001, paleontologist Kenneth D. Rose and colleagues described additional mammalian remains from the same fossil beds, which were tentatively assigned to *A. hottoni*.[4]

## Description

The [holotype](/source/Holotype) of *Arundelconodon* consists of a right [mandibular ramus](/source/Mandibular_ramus) (the upward-extending portion on the side of the lower jaw) with five teeth: two [premolars](/source/Premolar) and three [molars](/source/Molar_(tooth)). The two premolars are large in relation to the molars, with each possessing four [cusps](/source/Cusp_(anatomy)). The teeth range from 2.89 millimeters (0.114 in) to 3.43 millimeters (0.135 in) in length and 1.03 millimeters (0.041 in) to 1.30 millimeters (0.051 in) in width, all possessing two "well-divided" roots. The only preserved [alveoli](/source/Dental_alveolus) (tooth sockets) are those containing the teeth. The entirety of the preserved portion of the jaw is less than 25 millimeters (0.98 in) long. Cifelli and colleagues assigned the genus to the [family](/source/Family_(taxonomy)) [Triconodontidae](/source/Triconodontidae), with its distinguishing features including the size and shape of its [cusps](/source/Cusp_(anatomy)); its weak, discontinuous lingual (facing the tongue) [cingulid](/source/Cingulid) (a ridge found on the lower molars of certain mammals); an interlocking system between molars, where the front and back sides of the molars have a groove and a ridge, respectively, that extend from the [crown](/source/Crown_(tooth)) to the [root](/source/Root_(tooth)); and the presence of a [Meckelian groove](/source/Meckelian_groove), the last of which they described as noteworthy, as it is a basal ("primitive") feature found in many early mammals and their relatives that is absent from other North American Cretaceous triconodonts.[3]

The remains described in 2001 consist of two pieces of a jawbone, which the researchers believed could most likely be rejoined at the lower margin. Seven complete alveoli are preserved, representing [canine teeth](/source/Canine_teeth), molars, and premolars. As with the holotype, a distinct Meckelian groove is present. The researchers interpreted the specimen as representative of an immature individual. Despite its young age, the condition of the alveoli indicates that the premolar teeth are [permanent](/source/Permanent_teeth).[4]

## Classification

Cifelli and colleagues described *Arundelconodon* as an intermediate between [Jurassic](/source/Jurassic) and [Cretaceous](/source/Cretaceous) triconodontids, with some of its features advanced in comparison to genera from the Jurassic and earliest Cretaceous (such as *[Triconodon](/source/Triconodon)*, *[Trioracodon](/source/Trioracodon)*, and *[Priacodon](/source/Priacodon)*), while others are primitive in comparison to later Cretaceous triconodontids (such as *[Astroconodon](/source/Astroconodon)*, *[Corviconodon](/source/Corviconodon)*, and *[Jugulator](/source/Jugulator)*).[3] Since then, multiple phylogenetic studies have supported the placement of *Arundelconodon* as the most basal member of [Alticonodontinae](/source/Alticonodontinae), a [subfamily](/source/Subfamily) of Triconodontidae.[5][6]

## Paleoecology

[Early Cretaceous](/source/Early_Cretaceous) terrestrial [vertebrates](/source/Vertebrate) are poorly known globally. The discovery of *Arundelconodon* represented the first recorded Early Cretaceous mammal from the [Eastern Seaboard](/source/East_Coast_of_the_United_States) of the United States. Its discovery supports the idea that the terrestrial fauna of North America remained consistent throughout the Early Cretaceous, as it demonstrates no affinities with European or [Gondwanan](/source/Gondwanan) groups. The Arundel Clay, where it was first found, was dated to the [Aptian](/source/Aptian) age in its original description,[3] but later authors have labelled the formation as more likely early [Albian](/source/Albian). Other known vertebrates include [hybodonts](/source/Hybodont), [crocodylomorphs](/source/Crocodylomorph), [bony fish](/source/Bony_fish), [dinosaurs](/source/Dinosaur), [turtles](/source/Turtle), and another genus of mammal (*[Argillomys](/source/Argillomys)*). Aside from the hybodonts, which were likely tolerant of saltwater and consequently widely distributed, all [taxa](/source/Taxon) identified at the species level and several genera (including *Arundelconodon*) are [endemic](/source/Endemic) to the site. The deposits belong to the [Potomac Group](/source/Potomac_Group). The area has been interpreted as either a fringe swamp or, more recently, a [floodplain](/source/Floodplain) where fossils were preserved in the mud of isolated channels and [oxbow lakes](/source/Oxbow_lake). The presence of remains of various groups associated with coastal environments and the absence of [lissamphibians](/source/Lissamphibian), which are generally not saltwater tolerant, have been interpreted as indicative of a near-coastal environment.[7]

## See also

- [List of the Mesozoic life of Maryland](/source/List_of_the_Mesozoic_life_of_Maryland)

## References

1. ["Geologic Unit: Arundel"](https://ngmdb.usgs.gov/Geolex/Units/Arundel_171.html). *National Geologic Map Database*. USGS.

1. ["About Anne Arundel County"](https://www.aacounty.org/about). *Anne Arundel County*. Retrieved 15 April 2025.

1. Cifelli, Richard L.; Lipka, Thomas R.; Schaff, Charles R.; Rowe, Timothy B. (1999). ["First Early Cretaceous Mammal from the Eastern Seaboard of the United States"](https://www.jstor.org/stable/4523983). *Journal of Vertebrate Paleontology*. **19** (2): 199–203. [ISSN 0272-4634](https://www.worldcat.org/issn/0272-4634). Retrieved 20 January 2025.

1. Rose, Kenneth D.; Cifelli, Richard L.; Lipka, Thomas R. (22 August 2001). "Second triconodont dentary from the Early Cretaceous of Maryland". *Journal of Vertebrate Paleontology*. **21** (3): 628–632. [doi:10.1671/0272-4634(2001)021\[0628:STDFTE](https://doi.org/10.1671/0272-4634(2001)021%5B0628:STDFTE%5D2.0.CO;2)2.0.CO;2]

1. Kielan-Jaworowska, Zofia; Cifelli, Richard L.; Luo, Zhe-Xi (2004). *Mammals from the Age of Dinosaurs: Origins, Evolution and Structure*. New York: Columbia University Press. p. 248. ISBN 9780231509275.

1. Gaetano, Leandro C. & Rougier, Guillermo W. (July 2011). "New materials of *Argentoconodon fariasorum* (Mammaliaformes, Triconodontidae) from the Jurassic of Argentina and its bearing on triconodont phylogeny". *Journal of Vertebrate Paleontology*. **31** (4): 829–843. [doi:10.1080/02724634.2011.589877](https://doi.org/10.1080/02724634.2011.589877). [hdl:11336/68497](https://hdl.handle.net/11336/68497)

1. Frederickson, Joseph; Lipka, Thomas; Cifelli, Richard (2018). "Faunal composition and paleoenvironment of the Arundel Clay (Potomac Formation; Early Cretaceous), Maryland, USA". *Palaeontologia Electronica*. [doi:10.26879/847](https://doi.org/10.26879/847)

---
Adapted from the Wikipedia article [Arundelconodon](https://en.wikipedia.org/wiki/Arundelconodon) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Arundelconodon?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.