Picture of Thurston Lacalli

Thurston Lacalli B.Sc., Ph.D.

About me

Professor Emeritus, University of Saskatchewan

Visiting Professor (Biology), University of Victoria


Selected recent publications

  • Lacalli TC, 2021/22. An evolutionary perspective on chordate brain organization and function: insights from amphioxus, and the problem of sentience. Phil. Trans. Roy. Soc. B376/7: 20200520 (in press).
  • Lacalli TC, 2021. Innovation through heterochrony: an amphioxus perspective on telencephalon origin and function. Front. Ecol. Evol. 9: 666722.
  • Lacalli TC, 2021. Consciousness as a product of evolution: contents, selector circuits, and trajectories in experience space. Front. Syst. Neurosci. 15: 697129.
  • Lacalli TC, 2020. Evolving consciousness: insights from Turing, and the shaping of experience. Front. Behav. Neurosci. 14: 598561.
  • Lacalli TC, 2018. Amphioxus, motion detection, and the evolutionary origin of the vertebrate retinotectal map. EvoDevo 9: 6.  
  • Zieger E, Lacalli TC, Pestarino M, Schubert M & Candiani S, 2017. The origin of dopaminergic systems in chordates: insights from amphioxus. Int. J. Dev. Biol. 61: 749-761. 
  • Lacalli TC & Stach T, 2016. Acrania (Cephalochordata). In: Structure and evolution of invertebrate nervous systems. Eds: Schmidt-Rhaesa, A., Harzsch, S. and Purschke G. Oxford press, pp. 719-728.
  • Lacalli TC, 2012. The Middle Cambrian fossil Pikaia and the evolution of chordate swimming. EvoDevo 3:12.
  • Lacalli TC, 2010. The emergence of the chordate body plan: some puzzles and problems. Acta Zool. 91: 4-10.
  • Wicht H & Lacalli TC, 2005. The nervous system of amphioxus: structure, development, and evolutionary significance. Can. J. Zool. 83: 122-150.
  • Lacalli TC, 2005. Protochordate body plan and the evolutionary role of larvae: old controversies resolved? Can. J. Zool. 83: 216-224.
  • Lacalli TC, 2004. Sensory systems in amphioxus: a window on the ancestral chordate condition. Brain Behav. Evol. 64: 148-162.
  • Lacalli TC, 2001. New perspectives on the evolution of protochordate sensory and locomotory systems, and the origin of brains and heads. Phil. Trans. Roy. Soc. Lond. B356: 1565-1572.

See Documents & Links for a complete list


My research program while at the University was devoted to neuroanatomical studies of marine invertebrate larvae using serial EM reconstruction as a principal method. A number of phyla were examined and much of the data, in the form of negatives and selected photos, is lodged in the University Archives [see http://scaa.usask.ca/gallery/lacalli]. My particular focus, beginning in 1992, was a reconstruction of the anterior, brain-like region of the nerve cord of the invertebrate chordate Branchiostoma (amphioxus), to determine its suitablility as a model for the ancestral vertebrate brain. This was the most important of the projects completed in my lab during my tenure at the University of Saskatchewan, and resulted in a number of publications.

My zoological interests have always been broadly comparative and evolutionary. Since retiring, I've had the opportunity to address more general issues in my writing, relating to metazoan body plan, dorsoventral inversion, the organization of the chordate brain, and most recently, the origin of vertebrate consciousness. Much remains to be done on these topics.

I have also, over many years, had an interest in theoretical aspects of developmental pattern formation, with a focus on mechanisms that produce pattern by a combination of reactions and diffusional spread, so-called Turing models. An Introduction to the subject can be found in The Shaping of Life (Cambridge Press, 2010; see Documents & Links) by Lionel Harrison, a past collaborator and close colleague. There is much recent progress in this field on the theoretical side after decades of neglect, as the evidence for such mechanisms strengthens. My interest in nature at the microscopic level extends to the macroscopic scale, and samples of my efforts to do justice to this, via sketches and drawings of landscapes and such-like, are appended below in the Image Gallery.