This fossil is the oldest known preserved dinosaur cloacal vent.

3-D Reconstruction of Fossil Reveals Secret Sex Life of Dinosaurs

The newly discovered orifice is the oldest known fossilized cloacal vent in existence

The female giant panda Mei Xiang (pronounced may-SHONG) and male Tian Tian (tee-YEN tee-YEN), will return to China at the end of 2023 at the relatively elder panda ages of 25 and 26, respectively.

Smithsonian's Giant Pandas Will Continue to Cavort for Three More Years

A new agreement ensures that the Zoo’s beloved animals and the new cub can stay through 2023

Echidnas have a four-headed penis, though only two heads are put to use at a time.

Nine of the Weirdest Penises in the Animal Kingdom

A short list of some of nature’s most curious phalluses, from the echidna’s four-headed unit to the dolphin’s prehensile member

In the first days, Mei Xiang kept the cub mostly hidden, but a new photograph and video recently revealed the new arrival—born at 6:35 on August 21, 2020.

Giant Panda Mama Gives Birth to Baby Cub at National Zoo

The pink, squeaking infant is about the size of a stick of butter and will be named in 100 days

A male Thoropa taophora, pictured near Sununga beach in  Brazil.

This Frog Mates With Two Females in an Unusual Love Triangle

Relationships like these are rare among amphibians, scientists say

The comparatively massive female anglerfish (Melanocetus johnsonii) with her tiny mate permanently fused to her belly.

Anglerfish Drop Their Immune Defenses to Find Love

Male anglerfish are major clingers. To avoid mistaking mates as foreign tissue, the deep sea couples lost part of their immune system in evolution

Sperm swimming illusion when seen from above. The sperm tails seems to move symmetrically from one side to another. This view on how sperm moves was established since first observed by Antonie van Leeuwenhoek in 1677, more than three centuries ago.

Researchers Discover How Human Sperm Really Swim

A new 3-D microscopy study overturns hundreds of years of reproductive science

A fossilized Mussaurus egg that was the subject of one of two new studies documenting soft-shelled eggs at the time of the dinosaurs. Mussaurus was a long-necked, plant-eating dinosaur that grew to 20 feet in length and lived in modern-day Argentina between 227 and 208.5 million years ago.

First Soft-Shelled Dinosaur Egg Fossils Found

Twin discoveries reveal that some ancient reptiles laid soft-shelled eggs, challenging long-held assumptions in paleontology

Dr. Lucy Asher and her dog, Martha

For Dogs, Puberty Is Pretty Ruff, Too

Like human teenagers, a new study shows that canines exhibit heightened conflict behavior during adolescence

Male pug-nosed tree frogs confuse predators by overlapping their mating calls with those their neighbors.

Illusionist Frog Attracts Mates Without Unwanted Attention From Predators

The simultaneous mating calls of the male pug-nosed tree frog confuses bats but not female frogs

Dolphin Boy Bands Sing 'Pop' Songs in Sync—and the Ladies Want It That Way

Female dolphins, it seems, aren’t immune to the allure of a harmonizing boy band

Swamp wallabies can nourish three separate offspring at once: an older joey that's left the pouch, a young one nursing inside of it, and an embryo that has yet to be born.

Swamp Wallabies Can Get Pregnant While Pregnant

These marsupials can conceive during the final days of an ongoing pregnancy, creating a “backup” embryo ready to take its predecessor’s place

The first two cheetah cubs born via embryo transfer

In a First, Cheetah Cubs Born Through Surrogacy at the Columbus Zoo

Zookeepers and Smithsonian scientists successfully transferred cheetah embryos, marking a major conservation milestone for the vulnerable species

Two giraffes

Fourteen Fun Facts About Love and Sex in the Animal Kingdom

Out in the wild, flowers and candy just aren’t gonna cut it

Athena, a two-toed sloth who recently made her debut at the National Zoo.

Will Love Bloom Between Two Sloths at the National Zoo?

Keepers are gradually introducing Athena, who made her debut at the zoo in December, to fellow two-toed sloth Vlad. Sparks have not flown—yet

Birds Sniff Each Other's Bacteria to Help Choose a Mate

A new study finds the microbiome in a bird's preen oil determines its scent, which can impact its reproductive success

Mark Prausnitz holds an experimental microneedle contraceptive skin patch. Designed to be self-administered by women for long-acting contraception, the patch could provide a new family planning option.

Will Microneedle Patches Be the Future of Birth Control?

Researchers are developing a new long-acting, self-administered device that delivers hormones beneath the skin’s surface

Sandro Botticelli's "Birth of Venus" finds its subject striking a contrapposto pose

Why Viewers Are Drawn to Renaissance Artists' Go-To Pose

A new study finds that the contrapposto stance reduces the waist-to-hip ratio, an attribute popularly associated with attractiveness

The National Zoo's female panda Mei Xiang (above in 2019) is exhibiting signs of a possible pregnancy. These same behaviors could also mean she is experiencing a pseudopregnancy.

14 Fun Facts About Giant Pandas

Mother Mei Xiang’s annual ambiguous maternal behaviors always deliver heightened anticipation at the National Zoo

Dog Breeding Has Changed Pooches’ Brains

A new study has found that key anatomical differences in dogs’ brains are linked to the behaviors they were bred to perform

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