Alexander was a
Lecturer at the University College of North Wales (now
Bangor University) from 1958 to 1969 and then
Professor of Zoology at the
University of Leeds from 1969 until his retirement in 1999, when the title of
emeritus professor was conferred upon him.[8]
Until 1970, he was mainly concerned with fish, investigating the mechanics of
swim bladders, tails and
fish jaw mechanisms. Subsequently, he concentrated on the mechanics of
terrestrial locomotion, notably walking and running in
mammals, particularly on
gait selection and its relationship to
anatomy and the structural design of skeletons and muscles.[1]
Alexander was particularly interested in the mechanics of
dinosaur locomotion.[9] He developed a formula to calculate the speed of motion of dinosaurs, the so-called 'dinosaur speed calculator,' mathematically derived from the
Froude number:
"The key to deriving estimates of dinosaur gait and speed from trackways was provided by the zoologist R. McNeill Alexander (1976). From observations of modern animals, he derived a general relationship between an animal's speed of locomotion (v) and its hip height (h) and its stride length (SL), which is
Alexander also pointed out that this formula could be applied to dinosaur trackways since the stride length can be measured directly and the hip height could be estimated from the size of the foot print."[10]
Originally, Alexander stated: "I have now obtained a relationship between speed, stride length and body size from observations of living animals and applied this to dinosaurs to achieve estimates of their speeds. The estimated speeds are rather low—between 1.0 and 3.6 ms−1."[11]
Modifications to the original formula gave rise to revised estimates, and "Alexander (1996) argued that based on the bone dimensions of Tyrannosaurus it is unlikely they could have travelled at more than 8ms−1."[12] Several calculations using variants of the formula indicate that dinosaurs probably travelled at around 3 ms−1 with a top speed of 8 ms−1. This translates to a speed range of roughly 6–20 mph.
Alexander was secretary of the
Zoological Society of London (1992–1999) which included supervising the management of
London and
Whipsnade Zoos. He was president of the
Society for Experimental Biology (1995–1997), President of the International Society of Vertebrate Morphologists (1997–2001) and editor of the
Proceedings of the Royal Society B (1998–2004).[13] Alexander specialised in research on animal mechanics and published numerous books and research papers in the field from 1959.
^Alexander, R. McN. The Densities of Cyprinidae J Exp Biol 36, June 1959, pp. 333–340.
^Alexander, R. McN. Visco-elastic properties of the body-wall of sea anemones J. Exp. Biol. 39, 1962, pp. 373–386.
^Alexander, R. McN. (1964). "Adaptation in the skulls and cranial muscles of South American characinoid fish". Journal of the Linnean Society of London, Zoology. 45 (305): 169–190.
doi:
10.1111/j.1096-3642.1964.tb00493.x.
^Brandwood, A.; Jayes, A. S.; Alexander, R. McN. (2009). "Incidence of healed fracture in the skeletons of birds, molluscs and primates". Journal of Zoology. 208 (1): 55–62.
doi:
10.1111/j.1469-7998.1986.tb04708.x.