''Myotragus'' (

Neo-Latin New Latin (also called Neo-Latin or Modern Latin) is the revival of Literary Latin used in original, scholarly, and scientific works since about 1500. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy ...

, derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

: , and "Balearian mouse-goat"), is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of goat-antelope in the tribe

Caprini The subfamily Caprinae, also sometimes referred to as the tribe Caprini, is part of the ruminant family Bovidae, and consists of mostly medium-sized bovids. A member of this subfamily is called a caprine, or, more informally, a goat-antelope ...

which lived on the

Balearic Islands The Balearic Islands ( es, Islas Baleares ; or ca, Illes Balears ) are an archipelago in the Balearic Sea, near the eastern coast of the Iberian Peninsula. The archipelago is an autonomous community and a province of Spain; its capital is ...

Mallorca Mallorca, or Majorca, is the largest island in the Balearic Islands, which are part of Spain and located in the Mediterranean. The capital of the island, Palma, is also the capital of the autonomous community of the Balearic Islands. The Bale ...

and

Menorca Menorca or Minorca (from la, Insula Minor, , smaller island, later ''Minorica'') is one of the Balearic Islands located in the Mediterranean Sea belonging to Spain. Its name derives from its size, contrasting it with nearby Majorca. Its cap ...

in the western Mediterranean until its

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the Endling, last individual of the species, although the Functional ext ...

around 4,500 years ago. The fossil record of ''Myotragus'' on the Balearic Islands extends over 5 million years back to the early

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Messinian Salinity Crisis The Messinian salinity crisis (MSC), also referred to as the Messinian event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (d ...

. ''Myotragus'' is represented by a sequence of six sequential

chronospecies A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is p ...

representing a gradual change in morphology''.'' The youngest and best known species, ''M. balearicus,'' is noted for a number of unusual morphological adaptions, including forward facing eyes suggestive of

binocular vision In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...

, and a reptilian-like physiology. Early genetic research suggested that it was closely related to sheep of the genus '' Ovis'', however more recent research has indicated that its closest living relative is the takin (''Budorcas taxicolor''). ''M.'' ''balearicus'' became extinct when humans arrived in the Balearic Islands during the

3rd millennium BC The 3rd millennium BC spanned the years 3000 through 2001 BC. This period of time corresponds to the Early to Middle Bronze Age, characterized by the early empires in the Ancient Near East. In Ancient Egypt, the Early Dynastic Period is followe ...

History of discovery

The first remains of ''Myotragus'' were described by Dorothea Bate in 1909. Bate had been sent a letter by Robert Ashington Bullen, who informed her about a bone-bearing

breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of ...

deposit on the east of

, which prompted her to survey the island for

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

aged cave deposits. Three such deposits were found, which yielded fragmentary remains of ''Myotragus'', including a mostly complete skull, associated with a mandible and

atlas vertebra In anatomy, the atlas (C1) is the most superior (first) cervical vertebra of the spine and is located in the neck. It is named for Atlas of Greek mythology because, just as Atlas supported the globe, it supports the entire head. The atlas is t ...

, which was designated the type specimen of the new species and genus ''Myotragus balearicus''. In 1915,

Charles William Andrews Charles William Andrews (30 October 1866 – 25 May 1924) F.R.S., was a British palaeontologist whose career as a vertebrate paleontologist, both as a curator and in the field, was spent in the services of the British Museum, Department of Ge ...

described more material discovered in the intervening years, including material that had been discovered on

Description

Its eyes were not directed towards the sides, as are those of nearly all the

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

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 ...

s, but towards the front like nearly all

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter includin ...

s and carnivorans, granting them stereoscopic vision. The lower jaw contained two perennial-growth incisors, like

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

s and lagomorphs, but not other ungulates. The lower jaw usually lacked other incisors, though some jaws have been found with vestigial second incisors. The upper jaw lacked incisors. The rest of its teeth were molars and premolars, adapted to the crushing of vegetable matter. The nose was short in comparison with the rest of the skull, similar to the noses of rabbits and hares. Finally, both sexes had at the top of the head two very short horns. It is possible these horns were longer, having short bone-bases and long horn-covers, but no complete horns have been found. ''Myotragus balearicus'' was quite small in size (standing about at the shoulder) and weighed between . The legs were proportionately shorter than those of other related bovids, and less flexible, which did not make ''Myotragus balearicus'' exceptionally fast. This was not a serious problem because on the islands there were no predators except for some birds of prey, like the now-extirpated

golden eagle The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known bird ...

, from which they probably hid in the vegetation. On the shoulders they had a pronounced hump, while the back was bent in the hindquarters. The legs, like many from the order

Artiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

, had four fingers of which only two were used to walk. The tail was rather long in comparison to the rest of the body.

Species

Six sequential

of ''Myotragus'' have been named, representing 5 million years of gradual accumulated morphological change, including a reduction in body size and changes to the locomotor system, the teeth and the visual system. *''M. palomboi'' Bover, Quintana & Alcover, 2010 Early Pliocene, Mallorca *''M. pepgonellae'' Moyà-Solà & Pons-Moyà, 1982 Middle Pliocene, Mallorca *''M. antiquus'' Pons-Moyà, 1977 Late Pliocene, Mallorca *''M. kopperi'' Moya & Pons, 1980 Early Pleistocene, Mallorca *''M. batei'' Crusafont & Angel, 1966 Middle Pleistocene, Mallorca, Menorca *''M. balearicus'' Bate, 1909 Late Pleistocene-Holocene, Mallorca, Menorca

Paleobiology

Diet

Evidence from preserved

coprolite A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name is ...

s of ''M. balearicus'' indicates that it was likely a browser, and heavily dependent on the native

boxwood ''Buxus'' is a genus of about seventy species in the family Buxaceae. Common names include box or boxwood. The boxes are native to western and southern Europe, southwest, southern and eastern Asia, Africa, Madagascar, northernmost South ...

species ''

Buxus balearica ''Buxus balearica'', the Balearic boxwood, is a shrub or small evergreen tree typical of the Mediterranean forests, woodlands, and scrub, Mediterranean forest. It grows wild in Algeria, Morocco, the Island of Sardinia and Spain. Description ...

'' for a large part of its diet. The smooth texture of the coprolites indicates that the digestion was likely highly efficient.

Physiology and growth

The bone histology of ''M. balearicus'' shows lamellar-zonal tissue throughout the cortex, a feature otherwise typical of ectothermic reptiles. The growth of bones in ''Myotragus'' is unlike any other mammal and similar to crocodilians in showing slow and adaptive rates, intermittently ceasing growth altogether, and reaching somatic maturity by about 12 years. This pattern of growth indicates that ''Myotragus'', in the same way as extant reptiles, adapted its metabolism to changing food and water availability, and ambient temperatures.

Movement

An analysis of the phalangeal bones of ''M. balearicus'' found that the bones of the foot were tightly bound by

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal l ...

s and inelastic. This suggests that ''Myotragus'' was obligately a slow walker with a reduced step length, and lacked the ability to jump. The likely reason for this is as an energy saving measure, as the shock absorbing mechanism in the foot bones of other caprines requires large amounts of muscle energy. The proximal and medial phalanges were likely orientated vertically relative to the ground surface, which reduced bending stresses.

Senses

The

cranial endocast An endocast is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Endocasts can be artificially made for examining the properties of a hollow, inaccessible sp ...

of ''M. balearicus'' indicates that the areas of the brain and structures associated with vision, sound and smell were strongly reduced when compared with other caprines. These likely represent optimisations to the animals energy budget, which were unnecessary in the absence of terrestrial predators.

Origins

The unique characteristics of ''Myotragus balearicus'' are a consequence of a prolonged process of evolution on the islands (a clear example of island dwarfing). In this type of isolation, the ungulates tend to become smaller while

s and lagomorphs increase their size, as happened to the '' Hypnomys'', the giant

dormouse A dormouse is a rodent of the family Gliridae (this family is also variously called Myoxidae or Muscardinidae by different taxonomists). Dormice are nocturnal animals found in Africa, Asia, and Europe. They are named for their long, dormant hibe ...

that shared a habitat with ''Myotragus''. Such species also tend to lose their fear reaction towards predators if none occur on the islands. A clear example of this is the loss of the capacity to run at high speed, the development of stereoscopic vision (which is useful to calculate distances, but not so to watch for predators) and the proportional reduction of the brain. The analyses of DNA and the oldest fossils (

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Aragoral mudejar'' and '' Norbertia hellenica'' from the Late

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

of Europe. An analysis of complete mitochondrial genomes found that its closest living relative is the takin (''Budorcas taxicolor''), native to the eastern Himalayas with an estimated

divergence In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the quantity of the vector field's source at each point. More technically, the divergence represents the volume density of ...

around 7.1 million years ago. A

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

is given below. The ancestor of ''Myotragus'' likely arrived in the Balearic Islands during the

Messinian The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.333 ± 0.005 Ma (million years ago). It follows the Tortonian and is followed by the Zanclean, the fi ...

stage of the late Miocene at a time at which the

Strait of Gibraltar The Strait of Gibraltar ( ar, مضيق جبل طارق, Maḍīq Jabal Ṭāriq; es, Estrecho de Gibraltar, Archaic: Pillars of Hercules), also known as the Straits of Gibraltar, is a narrow strait that connects the Atlantic Ocean to the Medi ...

closed and the Mediterranean Sea evaporated, reducing sea level within the basin by 800–1200 metres, in an event called the

Messinian salinity crisis The Messinian salinity crisis (MSC), also referred to as the Messinian event, and in its latest stage as the Lago Mare event, was a geological event during which the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (d ...

, allowing a land connection between the Iberian Peninsula and the Balearics. Later on, the opening of the straits and the massive salt water inflow isolated the animal populations, which diversified in the new Mediterranean islands created by tectonic forces. At the same time, climatic change replaced the vegetation of subtropical type with the present one of Mediterranean type, forcing ''Myotragus'' to develop drastic changes in its feeding and set of teeth. ''Myotragus'' initially only colonized the island of Mallorca. On

Ibiza Ibiza (natively and officially in ca, Eivissa, ) is a Spanish island in the Mediterranean Sea off the eastern coast of the Iberian Peninsula. It is from the city of Valencia. It is the third largest of the Balearic Islands, in Spain. Its la ...

a strange ecosystem without terrestrial mammals developed in which birds and bats were the main vertebrates, while in Menorca a giant rabbit, '' Nuralagus rex'' evolved that covered the same niche as ''Myotragus'' in Mallorca. With the level of the sea falling due to glacial cycles during the

, Mallorca and Menorca were periodically connected and ''Myotragus'' replaced the great Menorcan lagomorphs. Both islands separated again at the beginning of the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

Extinction

Diverse datings indicate that the three native terrestrial mammals of Mallorca and Menorca (''Myotragus balearicus'', the giant dormouse ''

Hypnomys morpheus ''Hypnomys'', otherwise known as Balearic giant dormice, is an extinct genus of dormouse (Gliridae) in the subfamily Leithiinae. Its species are considered examples of insular gigantism. They were endemic to the Balearic Islands in the western Me ...

'' and the large shrew ''

Nesiotites hidalgo The Balearic shrew (''Nesiotites hidalgo'') is an extinct species of shrew from Majorca and Menorca, in the Balearic Islands of Spain, belonging to the endemic genus ''Nesiotites.'' It was one of three native land mammals to the Balearic Islands, ...

'') disappeared all in the same very short period of time, during the third millennium BC. Historically there was debate as to whether the extinctions were caused by climate change, or whether they were exterminated by the first human settlers of the Balearic Islands. The dominant theory is the one that postulates an extinction by human causes. Traditional methods had dated the first human colonization of the Balearic Islands towards 5000 BC or even before, but subsequent tests with modern methods of dating clearly indicate that there was no human presence before 3000 BC. This date agrees very closely with the fast decline of the three forms. The youngest remains of ''Myotragus'' date to around 2632 calibrated years BC, while the minimum date of human arrival on the Balearic Islands is currently 2282 BC. Extinction was likely rapid within less than 100 years of human arrival on the islands. In 1969 it was suggested that ''Myotragus'' shows signs of

domestication Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...

but was later found to have no empirical evidence supporting the idea.

References

{{DEFAULTSORT:Myotragus Balearicus Prehistoric caprids Prehistoric mammals of Europe Endemic fauna of the Balearic Islands Holocene extinctions Fossil taxa described in 1909 Prehistoric even-toed ungulate genera