Definition of "heterodont"

"On the Homologies and Notation of the Teeth of Mammalia," by W[illiam] H[enry] Flower, F.R.S. […] The classification and special homologies of the teeth of the heterodont mammals was next discussed.

1868, “Quarterly Chronicle of Microscopical Science”, in Edwin Lankester, George Busk, editors, Quarterly Journal of Microscopical Science, volume VIII (New Series; volume XVI overall), London: John Churchill and Sons, […], pages 277–278

The adaptation of the form of the teeth on both sides to this position, and the accurate adjustment of their contiguous surfaces, shows that it is a natural conformation. They are, moreover, of very nearly even height throughout the series, and in their configuration present a remarkable and gradual transition from the first incisor to the last molar, easily traced in both jaws, and more even and regular than in any other known heterodont mammal.

1873 June 19, William Henry Flower, “VI. On a Newly Discovered Extinct Ungulate Mammal from Patagonia, Homalodontotherium Cunninghami.”, in Philosophical Transactions of the Royal Society of London, volume 164, London: […] Taylor and Francis, […], published 1874, page 175

The few common characters by which the Edentata are associated are too well known to need repetition. The principal one is the abseance of any trace of the typical heterodont and diphyodont dentition, found in a more or less modified form in all other placental mammals.

1882 April 18, William Henry Flower, “On the Mutual Affinities of the Animals Composing the Order Edentata”, in Proceedings of the Scientific Meetings of the Zoological Society of London, number XXV, London: […] [Zoological] Society [of London]; Longmans, Green, Reader, and Dyer, […], page 359

[I]n many heterodont forms the teeth at the anterior end of the series of premolars and molars are small teeth, standing to the teeth behind them as the first terms of a series more or less regularly progressing in size.

1894, William Bateson, “Linear Series—continued”, in Materials for the Study of Variation Treated with Especial Regard to Discontinuity in the Origin of Species, London, New York, N.Y.: Macmillan and Co., page 269

The process of evolution of the specialised heterodont dentition of the Mammalia, or of the Theriodontia, from the simple homodont and polyphyodont dentition of the lower Reptilia would, I think, necessarily cause a reduction in number of the successional sets of teeth, due to an enlargement of one set and a consequent abstraction of growth, energy and material from the underlying sets.

1894 August 1, M. F. Woodward, “On the Succession and Genesis of Mammalian Teeth”, in W. H. Dolamore, editor, The Dental Record: A Monthly Journal of Dental Science, Art, and Literature, Devoted to the Interests of the Profession, volume XIV, number 8, London, Manchester: Dental Manufacturing Company, page 375

Finally the structure of the palate in ?Acrodus (and to a lesser extent, Hybodus and Asteracanthus) shows certain general resemblances to that of modern heterodont sharks, particularly in the lower postorbital ramus, absence of an orbital process, well-developed ethmoidal articulations and absence of a basal angle.

1981 April 2, Keith Stewart Thomson, “An Early Triassic Hybodont Shark from Northern Madagascar”, in Postilla, number 186, New Haven, Conn.: Peabody Museum of Natural History, Yale University, published 15 February 1982, page 13, column 1

Mammalian teeth are characteristically heterodont, i.e. teeth are dissimilar in shape and size.

2007 March, “Dentition in Mammals”, in Mahendra Jain, editor, Competition Science Vision: A Specialized Magazine for Medical Entrance & 10+2 Exams, volume 10, number 109, Agra, Uttar Pradesh: Mahendra Jain for Pratiyogita Darpan, page 76, column 2

The first cetaceans were heterodont and had multicusped cheek teeth. […] The earliest odontocetes were heterodont, and the earliest mysticetes retained teeth […], though vascular grooves on their palates suggest baleen too […].

2010, Peter S. Ungar, “Cenozoic Mammalian Evolution”, in Mammal Teeth: Origin, Evolution, and Diversity, Baltimore, Md.: Johns Hopkins University Press, part II (The Evolution of Mammal Teeth), page 120, column 1

In this sense all hinges are Heterodont, and the distinction drawn by [Melchior] Neumayr between Heterodont and Desmodont teeth, so far as their situation is concerned, resolves itself into a comparison between teeth originally laterals and both in one valve, with paired laminæ in the opposite valve, on the one side; and teeth originally cardinals, or, if laterals, then laterals of which one was in one valve and one in the other, with the clasping laminæ also alternated.

1895 March, William Healey Dall, “The Hinge Teeth”, in Contributions to the Tertiary Fauna of Florida, with Especial Reference to the Miocene Silex-beds of Tampa and the Pliocene Beds of the Caloosahatchie River (Transactions of the Wagner Free Institute of Science of Philadelphia; 3, part III), part III (A New Classification of the Pelecypoda), Philadelphia, Pa.: Wagner Free Institute of Science, […], page 491

I wish, however, at once to say, that a satisfactory solution will only be arrived at by actual observation of the development of the hinge of heterodont bivalves.

1899, Palaeontologica Indica: Memoirs of the Geological Survey of India, volume I, Calcutta, West Bengal: Geological Survey of India, page 7

The palaeoheterodonts are an extant, Ordovician–Recent, group characterised by heterodont to schizodont dentition. They are freshwater to marine. Palaeoheterodonts are exemplified by the heterodont modiomorphioid Modiolopsis, the freshwater unionoid Unio, and the schizodont trigonoids Trigonia, Myophorella and Neotrigonia.

2006, Robert Wynn Jones, “Principal Fossil Groups”, in Applied Palaeontology, Cambridge, Cambridgeshire: Cambridge University Press, page 124, column 2

[A]mongst heterodonts there are several Rodents which have no deciduous teeth, e.g., the rat; […] Among Marsupials, which are true heterodonts, there is only one milk molar on each side in each jaw; […]

1876, Charles S[issmore] Tomes, “The Teeth of Mammals”, in A Manual of Dental Anatomy, Human and Comparative, London: J[ohn] & A[ugustus] Churchill, […], pages 276–277

On the other hand, in the Mammalian orders with two sets of teeth, these organs are said to acquire fixed individual characters, to receive special denominations, and can be determined from species to species, being equivalent to the Heterodonts. The author [William Henry Flower] then showed that […] among the Heterodonts many were partially, and probably some completely, Monophyodonts.

1868, “Quarterly Chronicle of Microscopical Science”, in Edwin Lankester, George Busk, editors, Quarterly Journal of Microscopical Science, volume VIII (New Series; volume XVI overall), London: John Churchill and Sons, […], pages 277–278

We have Homodonts, or animals with teeth quite homogeneous in shape, and Heterodonts, those having teeth of dissimilar shapes, the large majority of mammals being Heterodonts.

1878 June, C. N. Peirce, “Proceedings of Dental Societies. Alumni Association of the Pennsylvania College of Dental Surgery. [The Varieties of Teeth Found in Animals; Their Muco-dermal Origin, and How the Blending of Their Different Forms in the Class Mammalia Favors the Theory that They are but Modifications from Some Common Ancestral Type.]”, in James W. White, editor, The Dental Cosmos: A Monthly Record of Dental Science. […], volume XX, number 6, Philadelphia, Pa.: Samuel S. White, […], page 320

In the aberrant Orycteropus (Aard-Vark), with ten adult teeth, [Oldfield] Thomas finds seven milk teeth behind the maxillary suture (thus taking us into the molar region of the typical heterodonts).

1894 January 4, “The Rise of the Mammalia in North America”, in Nature: A Weekly Illustrated Journal of Science, volume XLIX, number 1262, London, New York, N.Y.: Macmillan and Co., page 238, column 2

In the past, this would have been enough to allow one to suggest a close relationship between hybodonts and heterodonts. However, Campagno (1977) has recently attempted to show that hybodonts belong to a more derived position within the euselachians, specifically being allied with the galeoid oryctoloboids and lamnoids. If this is the case, the absence of the orbital process in heterodonts might be considered a highly derived condition and the overall close similarity of the palates of the two groups a convergence due perhaps to a common pattern of fore-and-aft jaw movements.

1981 April 2, Keith Stewart Thomson, “An Early Triassic Hybodont Shark from Northern Madagascar”, in Postilla, number 186, New Haven, Conn.: Peabody Museum of Natural History, Yale University, published 15 February 1982, page 13, column 1

The second suborder (Macrosformes) corresponds with the Heteroderms of M. André Marie Constant Duméril. These are divided into seven families: […] 4. the Heterodonts, (Dendrophis, Coronella, &c.); […]

1841, “REPTILES”, in [George Long], editor, The Penny Cyclopædia of the Society for the Diffusion of Useful Knowledge, volumes XIX (Primaticcio–Richardson), London: Charles Knight and Co., […], page 409, column 2