<p>Scientists have discovered a new 125-million-year-old fossil mammal in Spain that has pushed back the earliest record of preserved mammalian hair structures and inner organs by more than 60 million years.<br /><br /></p>.<p>The specimen, named Spinolestes xenarthrosus, was fossilised with remarkably intact guard hairs, underfur, tiny hedgehog-like spines and even evidence of a fungal hair infection.<br /><br />The unusually well-preserved fossil also contains an external ear lobe, soft tissues of the liver, lung and diaphragm.<br /><br />The microscopic structures of hair and spines in Spinolestes are the earliest-known examples in mammalian evolutionary history.<br /><br />"Spinolestes is a spectacular find. It is stunning to see almost perfectly preserved skin and hair structures fossilised in microscopic detail in such an old fossil," said study co-author Zhe-Xi Luo, professor of organismal biology and anatomy at University of Chicago.<br /><br />This Cretaceous furball displays the entire structural diversity of modern mammalian skin and hairs, he added.<br /><br />Spinolestes xenarthrosus lived in the Cretaceous period and belonged to an extinct lineage of early mammals known as triconodonts.<br /><br />The specimen measured roughly 24 cm in length and is estimated to have weighed around 50 to 70 grams, about the size of a modern-day juvenile rat.<br /><br />Its teeth and skeletal features indicate it was a ground-dweller that ate insects.<br />Spinolestes had remarkably modern mammalian hair and skin structures, such as compound follicles in which multiple hairs emerge from the same pore.<br /><br />It had small spines around a tenth of a millimeter in diameter on its back, similar to modern hedgehogs and African spiny mice which appeared to be formed by the fusion of filaments at follicles during development.<br /><br />The team even found abnormally truncated hairs that are evidence of a fungal skin infection known as dermatophytosis, which is widely seen among living mammals.<br /><br />Spinolestes is also the first example of a Mesozoic mammal in which soft tissues in the thoracic and abdominal cavities are fossilised.<br /><br />"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," Luo concluded.<br />The findings were described in a study published in the journal Nature.</p>
<p>Scientists have discovered a new 125-million-year-old fossil mammal in Spain that has pushed back the earliest record of preserved mammalian hair structures and inner organs by more than 60 million years.<br /><br /></p>.<p>The specimen, named Spinolestes xenarthrosus, was fossilised with remarkably intact guard hairs, underfur, tiny hedgehog-like spines and even evidence of a fungal hair infection.<br /><br />The unusually well-preserved fossil also contains an external ear lobe, soft tissues of the liver, lung and diaphragm.<br /><br />The microscopic structures of hair and spines in Spinolestes are the earliest-known examples in mammalian evolutionary history.<br /><br />"Spinolestes is a spectacular find. It is stunning to see almost perfectly preserved skin and hair structures fossilised in microscopic detail in such an old fossil," said study co-author Zhe-Xi Luo, professor of organismal biology and anatomy at University of Chicago.<br /><br />This Cretaceous furball displays the entire structural diversity of modern mammalian skin and hairs, he added.<br /><br />Spinolestes xenarthrosus lived in the Cretaceous period and belonged to an extinct lineage of early mammals known as triconodonts.<br /><br />The specimen measured roughly 24 cm in length and is estimated to have weighed around 50 to 70 grams, about the size of a modern-day juvenile rat.<br /><br />Its teeth and skeletal features indicate it was a ground-dweller that ate insects.<br />Spinolestes had remarkably modern mammalian hair and skin structures, such as compound follicles in which multiple hairs emerge from the same pore.<br /><br />It had small spines around a tenth of a millimeter in diameter on its back, similar to modern hedgehogs and African spiny mice which appeared to be formed by the fusion of filaments at follicles during development.<br /><br />The team even found abnormally truncated hairs that are evidence of a fungal skin infection known as dermatophytosis, which is widely seen among living mammals.<br /><br />Spinolestes is also the first example of a Mesozoic mammal in which soft tissues in the thoracic and abdominal cavities are fossilised.<br /><br />"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," Luo concluded.<br />The findings were described in a study published in the journal Nature.</p>