An interparietal bone (os interparietale or Inca bone or ''os inca var.'') is a

dermal bone A dermal bone or investing bone or membrane bone is a bony structure derived from intramembranous ossification forming components of the vertebrate skeleton including much of the skull, jaws, gill covers, shoulder girdle and fin spines rays ( l ...

situated between the parietal and supraoccipital. It is

homologous Homology may refer to: Sciences Biology *Homology (biology), any characteristic of biological organisms that is derived from a common ancestor *Sequence homology, biological homology between DNA, RNA, or protein sequences * Homologous chrom ...

to the postparietal bones of other animals. In humans, it corresponds to the upper portion of the squama of the

occipital bone The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the c ...

that lies superior to the highest

nuchal line The nuchal lines are four curved lines on the external surface of the occipital bone: * The upper, often faintly marked, is named the highest nuchal line, but is sometimes referred to as the Mempin line or linea suprema, and it attaches to the epi ...

and is completely fused to the supraoccipital. However, in some individuals this portion remains separate from the rest of the occipital bone throughout life. In such cases, this separate bone is particularly referred as Inca bone. Inca bones in humans were first found in the skulls of contemporary

indigenous peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

of the southern

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

as well as in those of

mummies A mummy is a dead human or an animal whose soft tissues and organs have been preserved by either intentional or accidental exposure to chemicals, extreme cold, very low humidity, or lack of air, so that the recovered body does not decay fur ...

of the

Inca civilization The Incas were most notable for establishing the Inca Empire in Pre-Columbian America, which was centered in modern day South America in Peru and Chile. It was about 2,500 miles from the northern to southern tip. The civilization lasted from 1 ...

. Although the Inca bone was originally encountered as a variation in South American and Latin American cranial remains, the variation occurs in people from all geographic regions of the world and is by no means indicative of South/Latin American origin. The existence of this Inca bone has helped to identify the mummified remains which spent 110 years in two German museums as belonging to a young South American woman who was probably a victim of ritual murder practiced around the 17th century.Reconstructing the Life of an Unknown (ca. 500 Years- Old South American Inca) Mummy
/ref> In many other mammals, this bone is completely fused to the supraoccipital as in humans. However in some mammals (for example, rodents, rabbits, and artiodactyls), this bone remains separate from the supraoccipital bone. Classic comparative anatomy have regarded the interparietal as being lost in various mammalian lineages since the interparietal and supraoccipital fuse with each other in the early ontogenetic period in many mammals, but recent study has shown that its presence is confirmed in all extant mammalian orders, particularly in the embryonic period (Koyabu and others, 2012).

References

{{Authority control Skeletal system

See also

References