The Starchild Skull exhibits both physical and genetic differences that distinguish it from a typical human skull.

An extensive range of conditions including Anophthalmia / Microphthalmia, Apert Syndrome, Cradleboarding (and other artificial cranial deformations), Cruzon Syndrome, Hydrocephaly, Morgellons Disease. Trisomy 13 (Patau Syndrome, Progeria (Hutchinson-Gilford Syndrome), and Trisomy 9 (Mosaic) have been examined as possible causes for the unusual characteristics of the Starchild Skull, but so far no condition or combination of conditions has been found that explains the skull.

List of Starchild Skull Abnormalities:

The bone is uniformly half as thick, or less, than normal human bone. It is not thin in a specific area or areas due to abnormality, it is thin all over.

The skull itself weighs half as much as human skulls of comparable size.

The surface of normal human bone is covered with tiny holes called lacunae, which perform the vital function of replacing old bone cells with new ones. The Starchild bone shows virtually no lacunae.

Inside the bone are microscopic “fibers” that may act to reinforce and strengthen the bone.

All bone is like a sandwich with hard cortical bone on the outside and porous cancellous bone that looks like a spone in the middle. The cancellous bone is where the bone marrow is stored. After death this marrow turns black and is consumed by micro-organisms. The cancellous holes of the 900 year old skull found next to the Starchild are completely empty, however the cancellous holes of the 900 year old Starchild bone contain traces of a red residue.

The lower face of the Starchild Skull is much smaller than a normal human.

It has no brow ridges, which all primates have. Its forehead is smoothly curved straight down to its upper eye sockets, unlike humans or any higher primate.

When a human forehead reaches its upper eye sockets, normally there is a sharp drop down to the pinched-together bones that create the upper nose. In the Starchild there is no drop. The nose extends straight and smooth from the forehead, staying wide and flat until the point where it is broken off, unlike that of humans and all higher primates

The Starchild Skull’s eye sockets are unusually shaped and are only 0.7 inches at maximum depth, compared to normal human eye sockets which average about 2 inches deep.

The optic foramens are the openings in the back of a human eye socket which let in the optic nerve and all the other nerves and blood vessels that “feed” each eyeball and allow it to function. In the Starchild Skull these are shaped and positioned differently.

The Starchild Skull had no frontal sinuses, an extremely rare condition.

All that remains of the Starchild’s lower face is the right side maxilla. The roof of its mouth was flat, lacking any sign of a normal human arch, and like all of the lower face, it is much smaller than that of a normal human.

The Starchild’s zygomatic arches (cheekbones) are broken off, but from the small fragments that remain it is clear that the space between the cheekbones and the other bones of the face is much smaller than it would be in a normal human. This is significant because the chewing muscles for the lower jaw pass through this space, and so must have been much smaller than in a normal human.

Human chewing muscles attach from the lower jaw to the side of the skull, extending over a large area of the skull. The starchild's chewing muscles The chewing muscles cover only about half as much of the skull.

The Starchild Skull’s ear holes are positioned lower on the head than in a normal human.

The Starchild’s inner ears are approximately twice the size of normal human inner ears.

The Starchild’s neck muscles attach in a way that indicates it was a very small neck relative to typical humans, no more than half of normal size.

Human neck muscles normally attach at an elevated point in the rear center of the occipital bone (the rear bone of the skull). That elevated point is called the “external occipital protuberance,” or “inion” for short. All humans, and indeed all primates on Earth, have an inion. The Starchild Skull does not.

In addition to the external occipital protuberance on the outside of the skull, there is an "internal occipital protuberance” on the inside. This functions like a shelf holding some of the weight of the brain. While the Starchild does have this internal shelf, it is much smaller than it would be in a normal human.

Though the rear of the Starchild Skull is widely expanded and greatly flattened, this is not the result of deliberate binding or cradleboarding. This was verified in 2004 br Dr Ted Robinson and his team.

At the top of the rear of the Starchild’s head is a noticeable “crease” at the rear of its saggital suture, where it meets the lambdoidal suture. The only possible way this can happen in a human skull is if there is abnormal fusion of the saggital suture. A CAT Scan showed that no such abnormal fusion exists in the Starchild Skull.

The Starchild Skull’s physical size is of a small adult in the range of 5 feet tall, or an average 12-year-old, which means its brain should be about 1200 cubic centimeters. An average adult has 1400 c.c. of brain. Instead the Starchild has 1600 c.c. of brain.

The teeth of the Skull are a controversial subject, as many experts feel they show the Starchild was a child of about 5 years old, however the biting surfaces of the teeth are worn and ground to a degree that seems impossible for such a young child, especially one with smaller than normal chewing muscles