From OMIM
Thanatophoric dysplasia is a severe short-limb dwarfism syndrome that is usually lethal in the perinatal period. Norman et al. (1992) classified cases of TD into subtypes based on the presence of curved as opposed to straight femurs; patients with straight, relatively long femurs always had associated severe cloverleaf skull and were designated TD type II (TD2), while TD cases with curved, short femurs with or without cloverleaf skull were designated TD type I (TD1) (Langer et al., 1987).  http://www.omim.org/entry/187600

From MedlinePlus Genetics
The term thanatophoric is Greek for "death bearing." Infants with thanatophoric dysplasia are usually stillborn or die shortly after birth from respiratory failure; however, a few affected individuals have survived into childhood with extensive medical help.

Researchers have described two major forms of thanatophoric dysplasia, type I and type II. Type I thanatophoric dysplasia is distinguished by the presence of curved thigh bones and flattened bones of the spine (platyspondyly). Type II thanatophoric dysplasia is characterized by straight thigh bones and a moderate to severe skull abnormality called a cloverleaf skull.

Thanatophoric dysplasia is a severe skeletal disorder characterized by extremely short limbs and folds of extra (redundant) skin on the arms and legs. Other features of this condition include a narrow chest, short ribs, underdeveloped lungs, and an enlarged head with a large forehead and prominent, wide-spaced eyes.  https://medlineplus.gov/genetics/condition/thanatophoric-dysplasia