During the 65 million years following the extinction of the dinosaur , the winner tarradiddle of the mammals has been more than a little unbalanced . placental ( placental mammals like dogs , horses , you and I ) had an evolutionary rager , exploding in diversityand fill vacant ecological roles across the Northern Hemisphere . Metatherians ( let in marsupials like kangaroos and koalas ) only got a small-scale foothold in the smaller , southern continents of South America and Australia . For tens of zillion of geezerhood , everything north of the equator seemed to be a land of full placental mammal authorization — but the fossilized remains of a khat - sized metatherian carnivore in Turkey are now challenging that story .
The fossilized skull and skeleton were unearth and collected from the Uzunçarşıdere Formation in Turkey ’s Central Anatolia realm , and described ina new newspaper in the journal PLOS ONEby research worker from the University of Washington and the UK ’s University of Salford . The remains represented a raw species — Anatoliadelphys maasae — which , due to its condition as a metatherian mammal , certain features of its underframe , and its age ( about 43 - 44 million class old ) was quickly recognized as an incredible breakthrough .
Anatoliadelphys was unlike any of its northern contemporaries , which are tiny , bug - eating critters . For one , it was big — weight roughly as much as a honeydew melon vine , Anatoliadelphys was an purchase order of order of magnitude more monolithic than any other northern metatherian mammal . It was also carnivorous , gird with burly jaw lined with furrowed premolars , allowing for a herculean bite that could have splintered bone or craunch the shells of panoplied invertebrate . base on depth psychology of Anatoliadelphys ’s skeletal frame , the cat - sized animal was in all probability an excellent social climber and grasper , and would have been at home in the tree . In life , Anatoliadelphys would have resembled something cognate to one of Australia’squollscrossed with apossum . However , instead of the adorable , wet - eyed pile of frivolity staring out at you from a Qantas leaflet , Anatoliadelphys would have been more like a mini pouched mammal tree diagram - hyaena , hungrily licking its osseous tissue - crushing chops while stalking prey in the canopy .
The uncovering of Anatoliadelphys rewrites a portion of the paleontological story of metatherian , showing that they occupy a position in the food web that was thought to be invariably the area of placental mammals in that one-half of the human race . This reality is typically explained by a possible competitive advantage in placental mammals . Indeed , the metatherian - ample southern Continent were conveniently isolate from the roiling caldron of northerly , placental competition , and when these two guilds finally met , it was the metatheriansthat mislay out .
moot what happened in the aftermath of the“Great American Interchange”—the movement of animals separately unique to North and South America three million years ago across the then - newly - formed Isthmus of Panama . Before this , South America hold fearsome metatherian carnivores have intercourse as “ borhyaenoids ” , which included wolf - like animals and Thylacosmilus , which was fundamentally an off - brand sabretooth cat . But shortly after North American placental carnivores like dog and khat migrate across the isthmus , these metatherians went extinct . Notably , Australia too has suffer extinctions of endemic marsupial ( likegiant wombatsandimmense , flat - faced kangaroos ) suspiciously close to the timing of first contact with placental invaders .
Suggestions as to why metatherians always seem to fall apart in these skirmish admit developmental constraints in theirshouldersandskull , have them less evolutionarily elastic — with these limitations , marsupials and their relative might be less able-bodied to accommodate to novel challenge . unburden by these anatomical restraint , placental mammal could utilise a larger evolutionary tool cabinet to acquire food , flee predators , and exploit their environs .
But Anatoliadelphys probably was n’t a struggle - inure exclusion , overreach the odds and rejecting the notion of metatherian free-enterprise “ inferiority . ” The secret to Anatoliadelphys ’s world may come up from geological and paleontological grounds that 40 million year - ago , its Anatolian home was an island . This island would have move as a refuge , allowing Anatoliadelphys to develop to fill a piranha niche with zero competition from placental mammals on the mainland . The fossil find is an amazing snapshot of the past , illuminating what was probable an ephemeral hold - out , a protect relic predominate behind enemy stock .
[ PLOS One ]
Jake Buehleris a Seattle domain science author with an idolisation for the Tree of Life ’s weird , furious , and unappreciated — follow him onTwitteror at hisblog .
AnimalsEvolutionPaleontologyScience
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