If you could go back in time to near the end of the Miocene epoch , around 8 million years ago , and pop along to the north of Australia , you might see some peculiar , libertine and – above all – massive birds sprint across the horizon . These beast were known as dromornithids , and their largest member , Dromornis stirtoni , was 3 metre ( 9.8 foot ) improbable and weigh around 500 kilograms ( 1,102 pound ) – 10 time that of an emu .
Having live extinct around 20,000 years ago , along withplenty of other megafauna , much about these flightless birds is a mystery . With this in mind , a new study , published in theJournal of Vertebrate Paleontology , has perhaps resolve one of the big enigmas of all : What on Earth was its sex activity life history like ?
As it turns out , it was something like that of a present-day goose ’s ; they were likely monogamous , having picked out a Ilex paraguariensis for liveliness . Both parent shared parental forethought and both sharply defended their nest . The international team of palaeontologist , led by researcher at Flinders University ( FU ) , manage to work all this out from a serial of bone sherd .
“ With their unnerving height and vast sizing , especially of male that may have exceeded 600 kilogram [ 1,323 pounds ] , they were up to of protecting the growing chick from predator , such as the frankfurter - sized transmissible thylacines and marsupial lions that were around at the time , ” Warren Handley , the lede generator of the study and a palaeobiologist at FU , articulate in astatement .
Australia ’s Northern Territory during the meter of these giant birds was a fond , plastered berth with coastal forests . Piotr Krzeslak / Shutterstock
The highly fractured and disunited bone of multipleD. stirtoni – also known as mihirungs or hell dust birds – were found by the team in a shrivel lachrymation golf hole in Alcoota within Australia ’s Northern Territory . This singular website contain a gem trove of fogey . Alongside the gargantuan birds , the well - uphold cadaver of several long - gone pouched mammal , cow - sized herbivore and Leo the Lion - same brute could also be seen within the cornucopia of worn - down corpses .
Separating theD. stirtonibones from the sleep , the team initially think they had discovered two new species of flightless bird . On closer examination , they make that one set belonged to a male person and the other to a female person . Specifically , specialized tissue paper was found only within the hollow , smaller bones of the female .
This tissue paper does n’t just name female from male – its existence within the medullary cavity is indicative of a female about to lay eggs . Themedullary bonetissue , as it is known , serves as a calcium reservoir for establish the hard parts of an eggshell .
At the very least , this demonstrate that these demon ducks were sexually dimorphic , in that the males were noticeably large than the females . The monolithic size of these boo also evoke that the less full-bodied female primarily guarded the eggs ; the front of multiple males at the site would imply that they stuck around for much of their aliveness , helping to guard any eggs or younglings . If this was the pillowcase , then it ’s likely that these birds mated for life .
An artist ’s mental picture of an grownup ward its untried . James Robins / DeAgostini / Getty Images
Based on the behavior of forward-looking equivalent , including the zany , the research worker assume that the Male often press using ritualize combat to assert laterality , and that the most prevailing male “ defended family grouping and priority district with a vengeance , ” backed up by their physically strong female mates .
Although much of this is supposition based on a rather special data set , palaentologists regularly compare out species to their modern similitude for control their conduct . In any case , if what they claim is true , you would n’t have wanted to issue forth face - to - face with one of these nimble and aggressive dromornithids . They are n’t sometimes called “ demon ducks of doom ” for nothing .
