Erik Helge Oswald Andersson, as his original name was, was born in the village of
Stensjö by in Döderhult parish in
Kalmar County, the son of Johan Fredrik Andersson (d.1907), a farmer, and his wife, Otilia Maria Erlandson (d.1940). He was educated at
Linköping Gymnasium. He then studied science at the
University of Uppsala, graduating BSc in 1912. He received his Ph.D. and a
docentship in paleontology from
Uppsala University in 1921 and became professor and keeper at the Zoopaleontological (later called the Paleozoological) department of the
Swedish Museum of Natural History in
Stockholm in 1923, a position he held until his retirement in 1959. Stensiö specialized in the anatomy and evolution of "lower"
vertebrates. His studies of
placoderms showed them to be related to modern
sharks (though, now, placoderms are considered to be the sister group of all jawed vertebrates, in addition to sharks). His first major work,
Triassic fishes from Spitzbergen (part I: Vienna 1921; part II: Stockholm 1925), was based on material collected during his expeditions to
Spitzbergen in 1912, 1913, 1915 and 1916. For his work,
The Downtonian and Devonian Vertebrates of Spitzbergen, Part I, Stensiö was awarded the
Daniel Giraud Elliot Medal from the
National Academy of Sciences in 1926. In 1917 he changed his name from Andersson to Stensiö, adopting the name of his home-town. He founded the so-called "Stockholm School" in paleozoology, continued notably by his successors in the professorship,
Erik Jarvik and
Tor Ørvig. Stensiö was a member of the
Royal Swedish Academy of Sciences from 1927 and was elected a Foreign Member of the
Royal Society in 1946. He received the
Wollaston Medal in 1953, and the
Linnean Medal of the
Linnean Society of London in 1957. He was awarded the
Linnean Society of London's prestigious
Darwin-Wallace Medal in 1958. He died on 11 January 1984 at the Danderyd Hospital in
Stockholm. ==Family==