More News to Swallow: Photos of “Marni and Barney”

Photos of the conjoined Barn Swallows mentioned in the previous post have been released.

After Paul took the birds to the vet to have them X-rayed, it was discovered that they were connected only through a piece of skin and shared no organs, Paul said. At first, it appeared the birds had only three legs between the two of them, but it turned out one leg was not developed properly and was tucked underneath.

Rowe said the birds would have had to come from a double-yolk egg.

If they were the product of a double-yolked egg, then they would be dizygotic twins. Conjoined twins are typically defined as monozygotic, since in mammals, it is not that two embryos join, rather that one zygote fails to divide completely and two embryos result.

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