From 1935 to 1944, Teodoras Bitvinskas attended primary school and gymnasium classes in Raseiniai and Lyduvėnai. Second World War Teodoras Bitvinskas with his family spent in Poland. In 1949, he entered the Faculty of Forestry at the Lithuanian Agricultural Academy and, in 1954, received a diploma as a forest economy engineer. From 1950–1955, Teodoras Bitvinskas worked at the Geology, Geography and Lithuanian Forest Institutes and from 1955–1960, at City, Agriculture and Industry Projection Institutes.
His first dendrochronological research was carried out in Biržai forests in 1953. From 1960–1962, under the supervision of Prof. Vaidotas Antanaitis (the Lithuanian Forest Projection Institute), Teodoras Bitvinskas collected a rich material on radial growth from Lithuanian forests. In 1962, Teodoras Bitvinskas entered doctoral studies in the Department of Forestry of the Lithuanian Agricultural Academy (scientific advisor - Prof. V. G. Nesterov). Doctoral dissertation Radial growth dynamics of pine forests and possibilities of the forecast was maintained on 19 May 1966. From 1966–1967, Teodoras Bitvinskas worked at the Lithuanian Forest Institute.
In 1968, Teodoras Bitvinskas founded a Group for Dendroclimatochronology at the Institute of Botany of the Lithuanian Academy of Sciences. The dissertation (Dr Habil.) The bioecological background of dendrochronology was maintained on 27 December 1985 at the Institute of Plant and Animal Ecology in Sverdlovsk. He was also the head of the Dendrochronological Data Bank of the Soviet Union and vice-chairmen of the Dendroclimatological Commission of the Soviet Union.
A picture from the Laboratory archive taken around the 1980s. The first row from left: Prof. A. Merkys (likely), Prof. Leonardas Kairiūkštis, Dr Teodoras Bitvinskas.
Teodoras Bitvinskas speaking with the local supervisor during the DendroProvenancing meeting in Tolieja (Molėtai District, Lithuania) in 2005.