Fossil of Ancient Hedgehog-like Creature Reveals Evolution of Hair and Spines
Posted on October 14, 2015
Scientists have discovered the fossil of an ancient hedgehog-like creature that has preserved fur shadows. The fossil (pictured below) is a well-preserved specimen of Spinolestes xenarthrosus. The 125-million-year-old fossil was preserved with intact guard hairs and even evidence of a fungal hair infection.
Hair follicles, organs, an ear lobe and soft liver and lung tissues were also preserved. The researchers say the microscopic structures of hair and spines observed in the fossil are the earliest-known examples in mammalian evolutionary history.
Zhe-Xi Luo, PhD, professor of organismal biology and anatomy at the University of Chicago and study co-author, says in a statement, "Spinolestes is a spectacular find. It is stunning to see almost perfectly preserved skin and hair structures fossilized in microscopic detail in such an old fossil. This Cretaceous furball displays the entire structural diversity of modern mammalian skin and hairs."
Spinolestes xenarthrosus lived in the Cretaceous period. It belonged to an extinct lineage of early mammals known as triconodonts. The specimen measured about 24 centimeters (9.4 inches) in length and weighed around 50 to 70 grams (.1 to .15 pounds). The spines on its back were about a tenth of a millimeter in diameters. The researchers believe it was an insect eating ground dweller based on its teeth and skeleton.
The researchers say the fossil find also indicates Spinolestes had dermal scutes, which are plate-like structures made of skin keratin. Modern creatures like armadillos and pangolins have more developed scutes. The creature also had extra articulations between vertebrae, which is similar to what is seen in the spinal columns of armored shrews and armadillos today.
Luo also says, "With the complex structural features and variation identified in this fossil, we now have conclusive evidence that many fundamental mammalian characteristics were already well-established some 125 million years, in the age of dinosaurs."
The fossil was found at the Las Hoyas Quarry in east-central Spain. This area was a lush wetland during the early Cretaceous. A research paper on was published here in the journal Nature.