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Male kalutas die from sex

A tiny marsupial found only in the arid, northwest Pilbara region mates so intensely that an entire generation of males can die off during a single breeding season, researchers said yesterday. Biologists studying kalutas — a mouse-sized marsupial — believe that they die en masse because of sex-driven immune system collapse. Female kalutas mate frequently and with different males during each breeding season. “That means that males also have to mate a lot, and have good quality sperm (and lots of it), to outcompete rival males,” said Genevieve Hayes, who led the University of Western Australia research team. “This intense investment in reproduction, evidenced by their large testes, appears to be fatal for males.” Scientists believe that it is a rare example of male semelparity — a reproduction strategy characterized by “synchronized death,” often before offspring are born. “Males were regularly captured in healthy numbers throughout the study, except immediately after the mating seasons, when no males were captured,” Hayes said. “This, coupled with other research in the field and laboratory, strongly suggests that males die after the mating season.” The researchers said that despite the kalutas’ “extreme mating behavior,” the species appears to be doing well.


Scientists discover dinosaur

Scientists have identified a new species of dinosaur from a nearly complete, 8m-long skeleton that was the largest ever discovered in the country. After analyzing hundreds of bones dating back 72 million years, the team led by Hokkaido University concluded that the skeleton once belonged to a new species of hadrosaurid dinosaur, a herbivorous beast that roamed the Earth in the late Cretaceous period. A partial tail was first found in northern Japan in 2013 and later excavations revealed the entire skeleton. The team named the dinosaur Kamuysaurus japonicus, which means “Japanese dragon god,” the university said in a statement. They believe the dinosaur was nine-year-old adult and would have weighed either 4 tonnes or 5.3 tonnes — depending on whether it walked on two legs or four. The discovery was published in British peer-reviewed journal Scientific Reports. “The fact a new dinosaur was discovered in Japan means there was once an independent world of dinosaurs in Japan or in East Asia, and an independent evolution process,” team leader Yoshitsugu Kobayashi said. K. japonicus probably lived in coastal areas, a rare habitat for dinosaurs at that time. The research raises the possibility that some species of dinosaurs “preferred to inhabit areas near the ocean, suggesting the coastline environment was an important factor in the diversification” of the dinosaurs in their early evolution, the university said.

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