High-resolution computed tomographic analysis of tooth replacement pattern of the basal neoceratopsian Liaoceratops yanzigouensis informs ceratopsian dental evolution

Abstract

The dental morphology and tooth replacement pattern of Liaoceratops yanzigouensis, the earliest known neoceratopsian, are important for our understanding of the evolution of the ceratopsian dental system. Here we describe the dental morphology and tooth replacement of Liaoceratops yanzigouensis based on high-resolution computed tomographic (CT) scan data of three specimens including the holotype, the first study for basal ceratopsian. The three-dimensional reconstructions reveal some important new information, including: three teeth in the premaxilla in one side, two more teeth in the dentary than in the maxilla, incipiently developed mesial grooves on some crowns, two generations of replacement teeth within some tooth families; and most functional teeth were under heavy resorption by the replacement process, but still remained functional. Comparisons of tooth pair positions from opposite sides in the four jaw quadrants of three specimens revealed a degree of bilateral symmetry in replacement pattern. Reconstruction of Zahnreihen yields an avergae z-spacing of 2.58 with simultaneous front-to-back tooth replacement. Our study presents the earliest evidence of derived neoceratopsian traits of the complex dental batteries in ceratopsids. Most significantly, our models reveal the tracts of partially resorbed functional teeth which appears to track the growth of the jaws, traits previously undocumented in Ceratopsia.

Tooth attachment and pleurodont implantation in lizards: Histology, development, and evolution

“…Kline and Cullum (1984) observed the same posterior migration of the tooth positions in their ontogenetic study of I. iguana, but by non-histological means. The histology and development of the interdental ridges in pleurodont squamates is identical to the interdental ridges, plates, and bone in other amniotes (LeBlanc & Reisz, 2013;LeBlanc et al, 2017b;Haridy et al, 2018;He et al, 2018).…”

Tooth development, histology, and enamel microstructure in Changchunsaurus parvus: Implications for dental evolution in ornithopod dinosaurs

“…parvus , given that several remnants of previous generations of teeth are embedded in the labial socket wall (Figs 2D and 3B–3F ). A similar phenomenon occurs in the dentition of the early neoceratopsian dinosaur Liaoceratops , where numerous root fragments are preserved within the jaws due to incomplete root resorption during the replacement cycle, which is a result of gradual tooth migration [ 24 ].…”

“…Herbivorous dinosaurs also faced the challenge of extensive tooth wear due to their abrasive diets [ 2 , 13 ]. Sauropods, neoceratopsians, and hadrosaurids circumvented this issue by maintaining a constantly replenishing grinding or shearing surface via rapid and coordinated tooth replacement [ 1 , 24 – 27 , 52 , 53 ]. Interestingly, Changchunsaurus parvus shows evidence of continuous tooth replacement, despite maintaining a fairly uniform shearing surface of imbricated tooth crowns to pulverize tough plant material [ 42 ].…”

New small-bodied ornithopods (Dinosauria, Neornithischia) from the Early Cretaceous Wonthaggi Formation (Strzelecki Group) of the Australian-Antarctic rift system, with revision ofQantassaurus intrepidusRich and Vickers-Rich, 1999

“…In addition to the original OTUs in the Dieudonné et al (2016) dataset, new OTUs included Diluvicursor pickeringi (see Herne et al, 2018), Galleonosaurus dorisae n. gen. n. sp., Leaellynasaura amicagraphica (see Rich and Rich, 1989), Owenodon hoggii (see Norman and Barrett, 2002; Galton, 2009), Qantassaurus intrepidus (see Rich and Vickers-Rich, 1999), and five marginocephalians ( Homalocephale calathocercos Maryanska and Osmolska, 1974, Stegoceras validum Lambe, 1902, Goyocephale lattimorei Perle, Maryanska, and Osmolska, 1982, Liaoceratops yanzigouensis Xu et al, 2002, and Protoceratops andrewsi Granger and Gregory, 1923 [Gilmore, 1924; Brown and Schlaikjer, 1940; Maryanska and Osmolska, 1974; Perle et al, 1982; Galton and Sues, 1983; Xu et al, 2002; Tanoue et al, 2009; He et al, 2018]). The addition of the marginocephalians arose out of the need to stabilize Cerapoda, identified as a problematically volatile node within a previous analysis (Herne et al, 2018).…”