Instances of attached identical twins are rarely found outside of humans.
Two heads are not always better than one, it seems.
These conjoined twin male bats were found in 2001 under a mango tree in southeastern Brazil. The person who found the already-deceased animals donated them to collections at the Federal Rural University of Rio de Janeiro. Last month, they were described in a publication by Marcelo Nogueira at the State University of Northern Rio de Janeiro.
“We believe the mother of these twins was roosting in this tree when she gave birth,” Nogueira explains.
Surprisingly, this specimen is the third example of conjoined bats found, but the phenomena is still poorly known outside of human beings. This is likely because so few of the animals probably survive. In people, twins being conjoined is typically a fatal condition over 80 percent of the time—and it may be higher among animals without medical or social support.
In people, where the phenomenon is well-studied, conjoined twins are still quite rare and only happen in 1 in 200,000 births in the United States. (Read more about two-headed sharks.)
The researchers believe these bats are newborn Artibeus bats from their physical characteristics, and also surmise they died at birth or were stillborn as their placenta is still attached.
An x-ray shows these male bats have separate heads and necks, but their spines eventually converge. They also have two similarly sized but separate hearts. (See a rare two-headed porpoise.)
Beyond just being an oddity, Nogueria explains, studying these bats can tell us more about their development.
“It is our hope that cases like this will encourage more studies on bat embryology, an open and fascinating field of research that can largely benefit from material already available in scientific collections.”
SummaryBeyond just being an oddity, Nogueria explains, studying these bats can tell us more about their development.
“It is our hope that cases like this will encourage more studies on bat embryology, an open and fascinating field of research that can largely benefit from material already available in scientific collections.”
Conjoined twinning is an embryological anomaly rarely reported in wild mammals and with only two previous records in Chiroptera. Here, we report a case of dicephalic parapagus conjoined twins in the Neotropical phyllostomid genus Artibeus. These twins are males and present separated heads and necks, but a conjoined trunk with an expanded upper thoracic region. They developed two complete forelimbs and two complete hindlimbs, all laterally to the trunk. There is a volume in the upper midback and between the heads that resembles a third rudimentary medial forelimb, but X-ray images only suggest the presence of medial skeletal elements of the pectoral girdle (clavicle and scapulae) in this region. The X-ray images also show that vertebral columns run separated from head until the base of lumbar region, where they form a single structure. Using ultrasound images, we detected the presence of two similarly sized and apparently separated hearts. The accumulation of study cases like this will help in the understanding of patterns and process behind this phenomena, and collection material plays a key role in this context.
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