In a serendipitous discovery, researchers have stumbled upon the revelation that every species within a mouse genus possesses tails reinforced with concealed bony scales. Until now, armadillos were the sole mammal group recognized for possessing such scales.
Live Science reported that this mouse genus is the Acomys, which includes 21 species of spiny mice and bears resemblance to ordinary mice from the Mus genus but is genetically closer to the rodent sub-family Gerbillinae, encompassing gerbils and sand rats. Spiny mice boast exceptionally rigid and coarse guard hairs that safeguard them against abrasion and moisture.
Bony Scales on Spiny Mice Just Like In Dinosaurs
Edward Stanley, a digital imaging specialist at the Florida Museum of Natural History, undertook a project called openVertebrae (oVert) that involved scanning spiny mice species. The project aimed to study 20,000 vertebrae specimens stored in museums and universities in the US.
With the help of specimens borrowed from his colleague, Malcolm Maden, a wildlife biologist at the University of Florida, Stanley, used a CT scanner to create detailed internal images.The scans unveiled the existence of osteoderms, which are bony scales hidden beneath the outer skin layer of the mice's tails.
Maden expressed his surprise at the discovery and said in a statement that he had given some of his spiny mice to Stanley for scanning, unaware of the presence of the rare bony plates in their tails. The fortuitous finding was a result of their simultaneous work in the same place on different projects.
Osteoderms are exceedingly uncommon among mammals, with armadillos being the only other known mammal genus possessing these bony scales that cover a significant portion of their bodies.
Although osteoderms are commonly found in reptiles like lizards and crocodilians, as well as certain frog species, and were a prominent feature among dinosaurs, especially Ankylosaurs that utilized their club-like tails in combat, it is probable that spiny mice utilize their bony tails primarily as a defense mechanism against predators rather than for offensive purposes.
The osteoderms found in the spiny mice tails bear a resemblance in shape and structure to those discovered in the fossilized remains of extinct sloths, which also possessed bony scales. This indicates that osteoderms have appeared in mammals before and suggests that the protective plates have evolved multiple times throughout the mammalian evolutionary tree, surpassing previous assumptions.
Development of Spiny Mice Osteoderms
According to Science Daily, researchers investigated the development of osteoderms in spiny mice, affirming their resemblance to the osteoderms of armadillos while proposing a separate evolutionary origin.
Using RNA sequencing, a genetic analysis method, researchers successfully identified the specific genes responsible for the formation of osteoderms in spiny mice. However, the exact reason behind this phenomenon remains unclear.
The study revealed that the mice deactivated genes involved in the production of keratin, a protein typically present beneath the skin in other mouse tails, as well as in human hair and nails. In contrast, they activated genes associated with osteoderms instead.
Maden expressed the team's desire to delve into the mechanisms by which the mice develop osteoderms, with the aspiration of eventually creating a laboratory-generated "armor-plated mouse."
The findings of the study, titled "Osteoderms in a Mammal the Spiny Mouse Acomys and the Independent Evolution of Dermal Armor," were published in the journal iScience on May 24.
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