ZoOLogy > In Pictures: Extreme Mammals

Hi, I'm John Flynn and I'm a paleontologist at the American Museum of Natural History in New York City. I research fossil mammals and the relationships between living and fossil mammals. I also curated an exhibition called Extreme Mammals. It showcases the biggest, smallest, and most amazing mammals of all time. Take a look at some unusual living and extinct mammals!

Cynognathus was an early relative of mammals. It lived about 235-250 million years ago.
Cat-sized Repenomamus was the largest known mammal from the Mesozoic "Age of Dinosaurs."
The extinct Tasmanian tiger was neither tiger nor dog. It was a marsupial!
Kangaroos can have 3 babies, in various stages of growth, at the same time.
Spectacled bears are born immature, weighing less than 1 pound at birth.
This extinct musk-ox species has horns four inches thick.
Male moose have antlers. Antlers can grow up to 2.5 cm (1 in) a day!
A canine of the extinct saber-tooth cat (Smilodon) can be up to 18 cm (7 in) long!
A beaver's incisors and molars never stop growing throughout their life.
Woolly mammoths had short, thin, densely packed hairs that helped keep them warm.
The shell of an extinct glyptodont could weigh over 500 kg (1,100 lbs)!
Marsupial sugar gliders have a skin membrane that keeps them aloft like a parachute.
Bats are the only mammals that can truly fly.
A male platypus has bony spurs on its hind legs that can deliver toxic venom.
Scale-covered pangolins can roll themselves into a ball when they feel threatened.
Opossums can use their prehensile or grasping tails to carry nesting materials or wrap around branches like a fifth leg.
Dugongs and manatees form the only living group of plant-eating marine mammals.
Humans are extreme mammals in some ways. We have very big brains and we walk upright on two legs.