#hyphalosaurus

[he-who-needs-to-be-silenced]

Fish of the yixian formation

With a scale

[justgoji]

Hyphalosaurus remake

[armadillorollup]

Two-headed calf, Laura Gilpin.  Hyphalosaurus lingyuanensis a fossilised reptile from the Cretaceous with two heads. 

[justgoji]

Hyphalosaurus lingyuanensis, an early Cretaceous Chinese aquatic reptile probably best known for a fossilized fetus that displayed a mutation that gave it two heads. This mutation can still occur in the reptiles of today, such as turtles and snakes.

With Hatsune Miku for scale:

[alphynix]

Polycephaly, the condition of having more than one head, is seen occasionally in modern animals. But due to its overall rarity, and the low chance of any given individual being fossilized, the odds of finding any ancient examples are incredibly low.

However, the aquatic choristodere reptile Hyphalosaurus lingyuanensis, from the Early Cretaceous of China (~122 mya), is a very common fossil. Thousands of specimens have been discovered, representing all stages of its life -- and among them is a single two-headed baby, the earliest known occurrence of polycephaly.

[opawesome-blog1]

GUYS LOOK IT'S ONE OF THE EARLIEST EXAMPLES OF DICEPHALUS 

THIS IS A HYPHALOSAURUS, A DIAPSID REPTILE FROM THE EARLY CRETACEOUS

THE PICTURES ARE PRETTY COOL BUT I DIDN'T KNOW IF I WAS ALLOWED TO PUT THEM DIRECTLY ON HERE SO CLICK THE LINK 

[palaeopedia]

The submerged lizard, Hyphalosaurus (1999)

Phylum : Chordata Class : Reptilia Order : Choristodera Family : Hyphalosauridae Genus : Hyphalosaurus Species : H. lingyuanensis, H. baitaigouensis

Early Cretaceous (123 - 122 Ma)

80 cm long (size)

Liaoning province, China (map)

Two specimens of Hyphalosaurus have been described with clear impressions of the skin. One specimen represents H. lingyuanensis, and the other (with clearer impressions) cannot be assigned to a species because part of the neck (the length of which is a key indicator of species) was destroyed when fossil dealers grafted a skull from a different specimen onto the slab. However, both specimens show nearly identical patterns of scales.

Hyphalosaurus was covered mostly in small, irregularly patterned polygonal scales, though these varied across the body. The scales of the hind legs were smaller, finer and more irregular than those of the torso, while the scales of the tail were nearly square and arranged in more regular rows. In addition to the small scales, two rows of large, round scutes with shallow keels ran along the animals sides. One row ran directly along the flank, with the other either slightly higher or lower and composed of scutes only 1/4 the size of the flank scutes. The flank row of larger scutes extended all the way to the base of the tail, and remained uniform in size across the entire row.

The tail itself has preserved soft tissue extending well beyond the margins of the skeleton. This, combined with the already flattened appearance of the tail vertebrae, suggests that a ridge of skin may have extended from the top and bottom of the tail creating a small fin. The feet and hands also appear to have been webbed.

Both Hyphalosaurus species were aquatic, a lifestyle reflected by their long necks and tails and relatively small limbs. Superficially, they resembled miniature plesiosaurs, though this resemblance arose convergently and does not reflect a close relationship. Hyphalosaurus was among the most aquatically adapted choristoderans, with smoother, flatter scales than its relatives, a tall and flattened tail for swimming, a long neck and webbed feet. Because the torso was fairly inflexible and the limbs were not particularly adapted for aquatic life, Hyphalosaurus probably swam using mainly its tall, flattened tail. The chest was barrel-shaped and made up of thick, heavy rib bones which would have helped Hyphalosaurus stay submerged.

Hyphalosaurus appears to have exclusively inhabited deep-water lakes. All specimens are preserved in silt characteristic of the deepest part of the lake environment, and are often preserved alongside deep-water fish and crustaceans. Hyphalosaurus is also conspicuously absent from the aquatic sediments of the Jiufotang Formation, which preserved a more swampy, shallow-water ecosystem.

Hyphalosaurus is the most abundant tetrapod (four-limbed vertebrate) in the Yixian Formation, and probably played an important role in the aquatic food chain. Its long and highly flexible neck and small, flattened skull indicates that it captured small prey animals like fish or arthropods using a sideways-strike, similar to modern aquatic predators with flattened skulls. Unlike other choristoderans, Hyphalosaurus was likely an active predator, rather than one that used a "sit and wait" ambush strategy. Its fossils are often found preserved alongside the small fish Lycoptera, which may have been a prey item, and at least one specimen preserved fish rubs as stomach contents. However, the lack of preserved stomach contents among the thousands of known specimens may indicate that they ate mainly soft-bodied prey.

[alphynix]

A 120 million-year-old example of polycephaly, found in China in 2006. This is a bizarrely two-headed fossil of a newborn Hyphalosaurus, a member of a group of extinct semi-aquatic reptiles known as choristoderes.

Hyphalosaurus lived in freshwater lakes, and their remains are so numerous that their entire lifespan is represented from embryos to fully grown adults. Females have even been found with developed embryos still inside their bodies, showing that they gave birth to live young.