Lieuwe Dirk Boonstra, palaeontologist, was the son of Gerrit Boonstra and his wife Margaretha Kuit. He received his secondary schooling in Durban and matriculated in 1923. He continued his studies at the University of Stellenbosch where he graduated as Bachelor of Science (BSc) in 1926 and Master of Science (MSc, with distinction) in palaeontology in 1928. In 1927 he was appointed as assistant in palaeontology at the South African Museum, Cape Town, for a period of three years to work on the accumulated pareiasaur material in its collection. His appointment was controversial as Dr E. C. N. van Hoepen* was attempting at this time to centralize all South African palaeontological research and collections at the National Museum, Bloemfontein, of which he was the director. As a result Boonstra's terms of employment stated that he was forbidden to do field work - an order he chose to ignore after the first year of his employment. During these years he completed a thesis on the osteology and myology of the pareiasaurian hind-limb, for which he was awarded the degree Doctor of Science (DSc) in 1936. When his contract expired in March 1930 he was given a permanent appointment as palaeontologist at the South African Museum, a position he held to his retirement in January 1972.
Boonstra devoted his entire scientific career to the fossil fauna of the Karoo, with particular emphasis on the earliest and most primitive mammal-like reptiles. For most of his career he was in sole charge of the South African Museum's collection of Karoo vertebrates. Through his extensive field work, initially often on foot , the collection grew from the nucleus established by R. Broom* and S. H. Haughton* to an extensive and representative record. His meticulous collecting and an ability to see value in every identifiable specimen formed the basis of important faunal and palaeo-ecological research. Most of his later research was concentrated on the Tapinocephalus zone, near the base of the Beaufort Group, which enabled him to contribute valuable insights on the origins and early radiation of the mammal-like reptiles. His approach was that of a comparative anatomist rather than that of a taxonomist, concentrating his efforts on establish faunal relationships and successions. To achieve this the wealth of morphological and faunal information that he collected was supplemented by his examination of related material in the United States, Britain and Russia. Particularly noteworthy was his comparison of the earliest South African mammal-like reptiles with their predecessors in Russia, during a visit to Moscow in 1962. These visits allowed him to suggest schemes for the origin and radiation of early mammal-like Karoo reptiles from Eurasian and American ancestors. His research formed the basis of some ninety publications, including a number of books and monographs. Most of his twenty or so papers published during the early years from 1929 to 1934 dealt with the Pareiasaurs, a clade of large, herbivorous parareptiles. Later papers dealt mainly with the creatures of the Tapinocehalus zone. He gave much attention to the post-cranial skeletons of the animals, and the limb and girdle muscle reconstructions. From these reconstructions he tried to recreate the posture and gait of the animals. He is credited with describing 26 new genera of fossil reptiles. Some of his papers dealt with fossil collections from Zimbabwe (1946), Lesotho (1947) and Tanzania (1953).
In the early nineteen-fifties Boonstra began to use his knowledge of the skeleton and inferred musculature of some Tapinocephalus zone reptiles to produce a series of striking life-size reconstructions of these reptiles set in dioramas depicting landscapes in Permian and Triassic times. This method of communicating years of specialist research in the simplest, but most correct manner to the scientist and greater public alike has proved useful in the study of the interaction between the animals and their environment and particularly on their probable behaviour. This work made him successful in generating public interest in palaeontology. However, the displays were a heavy burden on the museum's funds which led to a long and acrimonious quarrel between Boonstra and the museum's director at the time, Dr K. H. Barnard*. Nonetheless he was assisted by a preparator from 1958 onwards.
In recognition of his early contributions to palaeontology Boonstra was awarded the Queen Victoria Scholarship of Stellenbosch University in 1933, which enabled him to visit Europe and the United States in 1934-1935. During that time he was enrolled as a research student at University College, London, and made contacts that led to visits by several palaeontologists to South Africa. He was also awarded the Havenga prize in natural science and technology (biological division) of the Suid-Afrikaanse Akademie vir Wetenskap en Kuns in 1959. Volume 64 of the Annals of the South African Museum (1974) was dedicated to him. In 1939 he served as president of Section D of the South African Association for the Advancement of Science. Early in his career he made an appeal to ensure that palaeontological material should not be arbitrarily taken out of the country, which led to appropriate legislation in 1937.
Boonstra was married to Esme Elise Hoffman, with whom he had two sons and a daughter, but they were divorced about 1950. He subsequently married Irene ("Riensie") Vesta van der Merwe, with whom he had another son.
