Armadillos - continued...
In the 1900s the "polyembryony" became a crucial issue. This phenomenon was observed in certain parasites and other invertebrates, and by experimental intervention, in echinoderms and fishes. It was linked with the problem of the determination of sex and some authors reopened the case of armadillos, pointing out that, in all probability, the multiple twins of armadillo proceeded from a single egg. In 1909 Miguel Fernández, professor at La Plata University (Argentine), provided evidence for this hypothesis in the case of mulita (Fernandez 1909). At the same time, Horatio H. Newman and J. Thomas Patterson, zoologists from the University of Texas, published on the nine-banded armadillo of Texas (Newman and Patterson 1910).
The Zoological Laboratory of La Plata University (1927).
These papers were based on systematic research on the embryological development of these animals. At each development stage, a different organism was killed and dissected for examination. The growing of the embryonic structures could not be directly observed, it was only inferred after the fact that growth had taken place, deducing what was happening among the sequential slices of preserved moments (Hopwood 1999). This type of investigation required a great number of pregnant females in order to fix the earliest stages of the development and obtain reliable evidence. This turned out to be difficult since mulita and armadillo were non-domesticated mammals and species that reproduced once a year.
Reference: García, Susana . 2007. Armadillos and the issue of specific polyembryony. The Virtual Laboratory (ISSN 1866-4784), http://vlp.mpiwg-berlin.mpg.de/references?id=art72&page=p0002