''Mececyon trinilensis'', the Trinil dog, is an extinct

canid Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

species that lived on the island of Java in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

during the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

Description

The body size of ''Mececyon trinilensis'' been estimated at around , comparable to a

dhole The dhole ( ; ''Cuon alpinus'') is a canid native to South, East and Southeast Asia. It is anatomically distinguished from members of the genus ''Canis'' in several aspects: its skull is convex rather than concave in profile, it lacks a third ...

. This small size is the result of

insular dwarfism Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is disti ...

Habitat and ecology

''Mececyon trinilensis'' is endemic to the island of

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

. It was part of the Pleistocene Trinil Fauna of Java, which dates to the late

Early Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...

Middle Pleistocene The Chibanian, more widely known as the Middle Pleistocene (its previous informal name), is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocen ...

. Other animals of this

Faunal assemblage In archaeology and paleontology a faunal assemblage is a group of animal fossils found together in a given stratum. In a non-deformed deposition, fossils are organized by stratum following the laws of uniformitarianism and superposition, which stat ...

were ''

Bos palaesondaicus ''Bos palaesondaicus'' occurred on Pleistocene Java (Indonesia) and belongs to the Bovinae subfamily. It has been described by the Dutch paleoanthropologist Eugène Dubois in 1908.Dubois, E. (1908). Das Geologische Alter der Kendengoder Trini ...

'', the Indian muntjak (''Muntiacus muntjak''), '' Bubalus paleaeokerabau'', the Dubois santeng and ''

Stegodon ''Stegodon'' (from the Ancient Greek στέγω (''stégō''), meaning "to cover", and ὀδούς (''odoús''), meaning "tooth", named for the distinctive ridges on the animal's molars) is an extinct genus of proboscidean, related to elephants ...

trigonocephalus''. Other predators of the Trinil Fauna were the Trinil tiger (''Panthera tigris trinilensis'') and the

leopard cat The leopard cat (''Prionailurus bengalensis'') is a Felinae, small wild cat native to continental South Asia, South, Southeast Asia, Southeast, and East Asia. Since 2002 it has been listed as Least Concern on the IUCN Red List as it is widely di ...

(''Prionailurus bengalensis'').Christine Hertler/ Yan Rizal (2005): Excursion guide to the Pleistocene Hominid Sites in Central and East Java, Johann Wolfgang Geothe-Universität, Frankfurt am Main, Germany/ ITB, Bandung, Indonesia ''Mececyon'' is suggested to have been a

hypercarnivore A hypercarnivore is an animal that has a diet that is more than 70% meat, either via active predation or by scavenging. The remaining non-meat diet may consist of non-animal foods such as fungi, fruits or other plant material. Some extant exampl ...

. It has been estimated that ''Mececyon trinilensis'' hunted prey of 1 kg to 10 kg, preferably 5 kg in size. However this number could vary, because it is yet unknown if the ''Mececyon trinilensis'' hunted in packs, or if carrion left over by the Trinil tiger influenced its feeding habits. Likely prey included rats and birds.

Evolution

''Mececyon trinilensis'' probably ultimately originated from the mainland ''

Xenocyon ''Xenocyon'' ("strange dog") is an extinct group of canids, either considered a distinct genus or a subgenus of ''Canis''. The group includes ''Canis'' (''Xenocyon'') ''africanus'', ''Canis'' (''Xenocyon'') ''antonii'' and ''Canis'' (''Xenocyon'') ...

'', perhaps '' Xenocyon lycanoides'', likely via the intermediate species '' Megacyon merriami,'' which is proportionally larger than mainland ''Xenocyon'' species'','' and known from older Early Pleistocene fossils on Java. The similarly dwarfed

Sardinian dhole The Sardinian dhole (genus ''Cynotherium'' especially ''C. sardous'') is an extinct insular canid which was endemic to what is now the Mediterranean islands of Sardinia and Corsica during the Middle-Late Pleistocene. It went extinct at the end of ...

(''Cynotherium sardous'') is also suggested to have evolved from ''Xenocyon''. Its closest living relatives are the

African wild dog The African wild dog (''Lycaon pictus''), also called painted dog and Cape hunting dog, is a wild canine native to sub-Saharan Africa. It is the largest wild canine in Africa, and the only extant member of the genus '' Lycaon'', which is disti ...

(''Lycaon pictus)'' and the

(''Cuon alpinus''). Some authors have suggested sinking ''Mececyon'' and ''Megacyon'' into ''Xenocyon''. During the early Middle Pleistocene, the extinct dhole species ''Cuon priscus'' arrived on Java. It has been suggested that ''C. priscus'' outcompeted ''M/X. trinilensis,'' resulting in its absence in younger deposits.

References

{{Taxonbar, from=Q3853467 Prehistoric canines Pleistocene mammals of Asia Extinct animals of Indonesia