The remarkable dynamics in the establishment, rearrangement, and loss of dentition during the ontogeny of the sterlet sturgeon

Abstract

Background: Sturgeons belong to an early-branching lineage often used as a proxy of ancestor-like traits of ray-finned fishes. However, many features of this lineage, such as the transitory presence and the eventual loss of dentition, exemplify specializations that, in fact, provide important information on lineage-specific evolutionary dynamics.Results: Here, we introduce a detailed overview of the dentition during the development of the sterlet sturgeon. The dentition is composed of tooth fields at oral, palatal, and anterior pharyngeal regions. Oral fields are single-rowed, non-renewed and are shed early. Palatal and pharyngeal fields are multi-rowed and renewed from the adjacent superficial epithelium without the presence of the successional dental lamina. The early loss of oral fields and subsequent establishment of palatal and pharyngeal fields leads to a translocation of the functional dentition from the front to the rear of the oropharyngeal cavity until the eventual loss of all teeth.Conclusions: Our survey shows the sterlet dentition as a dynamic organ system displaying differential composition at different time points in the lifetime of this fish. These dynamics represent a conspicuous feature of sturgeons, unparalleled among extant vertebrates, and appropriate to scrutinize developmental and evolutionary underpinnings of vertebrate odontogenesis.

What is missing from the sturgeon jaw: Developmental morphology of the upper jaw in Acipenser

“…At the beginning of active feeding, the jaw arch has basically reached definitive state. Major changes, which occur in further development concern tooth resorption (see Pospisilova et al, 2021; Sewertzoff, 1926), the enlargement of the medial part of the maxilla into a broad spoon‐like plate and the development of the longitudinal lamina on the inner face of the bone (see Figure 2).…”

“…Since Gegenbaur, the broad ‘autopalatine’ plate of sturgeons has been equated with pars autopalatina (Arratia & Schultze, 1991; Bemis et al, 1997; Hilton et al, 2011, 2020; Pospisilova et al, 2021). This means that the entire palatoquadrate of sturgeons is homologous to the palatoquadrate of other actinopterygians.…”

“…The interpretation of the sturgeon maxilla as a dermopalatine has been uncritically accepted by the majority of researchers and shortly spread across diverse fields of sturgeon and paddlefish research (Bemis et al, 1997; Carroll & Wainwright, 2003; Eagderi et al, 2015; Eshaghzadeh et al, 2017; Findeis, 1997; Gardiner et al, 2005; Grande & Hilton, 2006; Hilton et al, 2011, 2015, 2020, 2021; Hilton & Forey, 2009; Hilton & Schaefer, 2002; Jin, 1999; Lu et al, 2005; Pospisilova et al, 2021; Smith et al, 2015; Warth et al, 2017). The only attempt to challenge this view was that by Datovo and Rizzato (2018), but without affecting the prevailing terminology (e.g.…”