The development of nasal turbinal morphology of moles and shrews

Abstract

The phylogenetic relationships of major groups within the Order Eulipotyphla was once highly disputed, but the advent of molecular studies has greatly improved our understanding about the diversification history of talpids, soricids, erinaceids, and solenodontids. Their resolved phylogenetic relationships now allow us to revisit the turbinal and lamina evolution of this group. The inner structure of the nasal cavity of mammals is highly complicated and the homologies of the turbinals among mammalian species are still largely unsettled. In this regard, investigation on fetal anatomy and ontogenetic changes of the nasal capsule allows us to evaluate the homologies of the turbinals and laminae. We observed various fetuses and adults of talpids and soricids using high-resolution diffusible iodine-based contrast-enhanced computed tomography (diceCT) and reviewed previous reports on erinaceids, solenodontids, and other laurasiatherians. Although the turbinal and lamina morphology was previsouly considered to be similar among eulipotyphlans, we found phylogenetic patterns for talpids and soricids. The nasoturbinal of the common ancestor of talpids and soricids was most likely rostrocaudally elongated. The epiturbinal at the ethmoturbinal II disappeared in soricids independently. Finally, we propose two possible scenarios for the maxilloturbinal development: 1) the maxilloturbinal of talpids and soricids became small independently with a limited number of lamellae as a result of convergent evolution, or 2) the common ancestor of talpids and soricids already had a small and simple maxilloturbinal.

Localized Expression of Olfactory Receptor Genes in the Olfactory Organ of Common Minke Whales

“…Upon removing the skeletal tissues of the medial nasal turbinals (ethmoturbinals I and II), the laterally positioned turbinals became visible. The anatomical nomenclature used to identify the nasal turbinals was based on Ito et al [78] and supplemented by relevant references [77,79].…”

Turbinal bones are still one of the last frontiers of the tetrapod skull: hypotheses, challenges and perspectives

“…This is due to several reasons like focusing on the so-called "stadium optimum", in placentals corresponding to fetal stages with fully developed chondrocranium, but also to technical limitations as histological techniques are limited by the ossification in older stages or simply by size (Maier and Ruf 2014). Nowadays, these barriers can be mostly overcome by CT technologies (e.g., Van Valkenburgh et al 2011Macrini 2012;Ruf et al 2015;Smith et al 2016;Martinez et al 2018Martinez et al , 2020Martinez et al , 2023aWagner and Ruf 2019;Ruf 2020;Ito et al 2021Ito et al , 2022Smith and Bonar 2022), although large species of Afrotheria, Carnivora, Artiodatcyla or Perissodactyla are still not in the focus of detailed morphological analyses of the turbinal complex. Thus, the homology of turbinals remains unclear in several species and grundplan reconstructions of specific clades are still pending.…”

“…It is especially true for species with highly complex olfactory turbinal bones such as armadillos, elephants or tapirs (e.g., Paulli 1900b;Hautier et al 2019). In some cases, examination of young individuals is sufficient because the complexity and number of turbinals is not changing in postnatal ontogeny (Ruf 2020;Ito et al 2021Ito et al , 2022. However, precise developmental studies are necessary in most cases.…”

“…However, precise developmental studies are necessary in most cases. To date, comprehensive and comparative developmental studies remain rare and limited to certain species and families (Smith and Rossie 2008;Smith et al 2016Smith et al , 2021cRuf 2014Ruf , 2020Ito et al 2021Ito et al , 2022Wagner and Ruf 2021). Therefore, more developmental studies will be necessary in the near future to further test hypotheses of turbinal homology (Maier and Ruf 2014).…”

“…Due to the difficulty to identify these two cartilaginous turbinals even with diceCT scans (Fig. 15, e.g., Ito et al 2022), these turbinals remain widely understudied.…”