''Fruitafossor'' was a

termite Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattode ...

-eating

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

endemic to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

during the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

epoch (around 150 mya). The description is based on a complete skeleton of a

chipmunk Chipmunks are small, striped rodents of the family Sciuridae. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia. Taxonomy and systematics Chipmunks may be classified either as ...

-sized animal. It was discovered on March 31, 2005, in

Fruita, Colorado The City of Fruita is a home rule municipality located in western Mesa County, Colorado, United States. The city population was 13,395 at the 2020 United States Census. Fruita is a part of the Grand Junction, CO Metropolitan Statistical Area a ...

. It resembled an

armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...

(or

anteater Anteater is a common name for the four extant mammal species of the suborder Vermilingua (meaning "worm tongue") commonly known for eating ants and termites. The individual species have other names in English and other languages. Together with ...

) and probably ate colonial insects in much the same manner as these animals do today. Other skeletal features clearly show that ''Fruitafossor'' was not related to armadillos, anteaters, or any modern group of mammal. This indicates that specializations associated with feeding on ants or termites have independently evolved many times in mammals: in ''Fruitafossor'', anteaters,

numbat The numbat (''Myrmecobius fasciatus''), also known as the noombat or walpurti, is an insectivorous marsupial. It is diurnal and its diet consists almost exclusively of termites. The species was once widespread across southern Australia, but ...

aardwolves The aardwolf (''Proteles cristata'') is an insectivorous species of hyena, native to East and Southern Africa. Its name means "earth-wolf" in Afrikaans and Dutch. It is also called maanhaar-jackal (Afrikaans for " mane-jackal"), termite-eatin ...

aardvark The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlike ...

pangolin Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: '' Manis'', '' Phataginus'', and '' Smut ...

s, and

echidna Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...

Description

In 2009, a study by J. R. Foster was published that estimated the body masses of

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

from the Late Jurassic

Morrison Formation The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...

using Use may refer to: * Use (law), an obligation on a person to whom property has been conveyed * Use (liturgy), a special form of Roman Catholic ritual adopted for use in a particular diocese * Use–mention distinction, the distinction between using ...

the ratio of dentary length to body mass of modern marsupials as a reference. Foster concludes that ''Fruitafossor'' was the least massive of the formation at 6 grams, much lower than the average Morrison mammal of 48.5 grams.

"Armadillo teeth and Popeye arms"

The teeth of ''Fruitafossor'' bear a striking resemblance to modern armadillos and aardvarks. They were open-rooted, peg-like teeth without enamel. This type of tooth is present today in insectivorous mammals, particularly those that are highly specialized to feed on colonial insects. This is termed "

myrmecophagy Myrmecophagy is a feeding behavior defined by the consumption of termites or ants, particularly as pertaining to those animal species whose diets are largely or exclusively composed of said insect types. Literally, myrmecophagy means "ant eating" ...

". Since

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...

s had not yet evolved at the time of ''Fruitafossor'', it is assumed that these animals fed on

s, which were abundant – along with their relatives, the

cockroach Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...

es. ''Fruitafossor'' has been nicknamed

Popeye Popeye the Sailor Man is a fictional cartoon character created by E. C. Segar, Elzie Crisler Segar.fossorial A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees. Prehistoric eviden ...

, employing scratch digging like modern

moles Moles can refer to: * Moles de Xert, a mountain range in the Baix Maestrat comarca, Valencian Community, Spain * The Moles (Australian band) *The Moles, alter ego of Scottish band Simon Dupree and the Big Sound People *Abraham Moles, French engin ...

gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...

s, and spiny anteaters. The

olecranon The olecranon (, ), is a large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon ...

process was highly enlarged indicating the forelimb had powerful muscles. This feature also supports the idea that they were myrmecophagous, as modern mammals employ this technique to break into termite mounds. Its vertebral column is also very similar to armadillos, sloths, and anteaters (order

Xenarthra Xenarthra (; from Ancient Greek ξένος, xénos, "foreign, alien" + ἄρθρον, árthron, "joint") is a major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Ex ...

). It had extra points of contact among

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

similar to the xenarthrous process that are only known in these modern forms. These processes generate a rigid and relatively inflexible backbone, which is good for digging. This find is an important discovery in mammal evolution, because of where it fits in the evolutionary tree of mammals and because of its

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...

. Most mammals of the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...

were

omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...

s or unspecialized

insectivore A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...

s. ''Fruitafossor'' is unique in the degree of specialization, both for digging and in regard to how specialized it was on insects. This fossil, along with others such as ''

Repenomamus ''Repenomamus'' (Latin: "reptile" (reptilis), "mammal" (mammalis)) is a genus of opossum- to badger-sized gobiconodontid mammal containing two species, ''Repenomamus robustus'' and ''Repenomamus giganticus''. Both species are known from fossils f ...

'', ''

Volaticotherium ''Volaticotherium antiquum'' (meaning "ancient gliding beast") is an extinct, gliding, insectivorous mammal that lived in Asia during the Jurassic period, around 164 mya. It is the only member of the genus ''Volaticotherium''. The discovery of ...

'', and ''

Castorocauda ''Castorocauda'' is an extinct, semi-aquatic, superficially otter-like genus of docodont mammaliaforms with one species, ''C. lutrasimilis''. It is part of the Yanliao Biota, found in the Daohugou Beds of Inner Mongolia, China dating to the M ...

'', challenge the notion that early mammals and mammaliaforms were restricted to a single niche and demonstrate that at least some early specialization occurred. The

eutriconodont Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia, Africa, Europe, North and South America during the Jurassic and the Cretaceous periods. The order was named by Kermack ''et al.'' in 1973 as a replacement name for the ...

Spinolestes ''Spinolestes'' is an extinct mammal genus from the Early Cretaceous of Spain. A gobiconodontid eutriconodont, it is notable for the remarkable degree of preservation, offering profound insights to the biology of non-therian mammals.Thomas Marti ...

'' may have also occupied a similar ecological niche, and like ''Fruitafossor'' it has xenarthrous vertebrae convergent with those of xenarthrans.

Classification and phylogeny

''Fruitafossor'' has no modern relatives. It is an early offshoot of mammal related to

theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. Ch ...

ns (the subclass containing

marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...

s and

placental Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsup ...

s). It has a unique suite of therian and

prototheria Prototheria (; from Greek πρώτος, ''prōtos'', first, + θήρ, ''thēr'', wild animal) is a subclass to which the orders Monotremata, Morganucodonta, Docodonta, Triconodonta and Multituberculata have been assigned, although the validity ...

n characteristics. Its shoulder-girdle is similar to a

platypus The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal Endemic (ecology), endemic to Eastern states of Australia, eastern Australia, including Tasmania. The platypu ...

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

, but many other features are more similar to most other modern mammals. This has led researchers to suggest that it may have been the earliest known relative to the evolutionary line leading to Theria. The genus name, ''Fruitafossor'', comes from Fruita, Colorado, where it was discovered. The suffix "fossor" indicates the fossorial, or digging, specialization of the forelimbs. The specific epithet, ''windscheffeli'', is in honor of Wally Windscheffel, who discovered the specimen along with Charles E. Safris of Des Moines, Iowa.

References

External links

''Science'' article on ''Fruitafossor''
* ttps://web.archive.org/web/20070312101934/http://www.carnegiemnh.org/news/05-jan-mar/fossil/ Carnegie Museum of Natural History Newsbr>BBC NEWS , Science/Nature , Termite eater lived with dinos
{{Taxonbar, from=Q2420570 Myrmecophagous mammals Prehistoric mammal genera Morrison mammals Jurassic mammals of North America Fossil taxa described in 2005 Taxa named by Zhe-Xi Luo Taxa named by John R. Wible

Description

"Armadillo teeth and Popeye arms"

Classification and phylogeny

See also

References

External links