The anterior process of the malleus in extant Lagomorpha (Mammalia)

Abstract

The anterior anchoring of the malleus of 30 extant species of Lagomorpha (rabbits, hares, pikas) has been studied on the basis of histological serial sections and µCT-scans. It is shown that former studies of Oryctolagus, Lepus, and Ochotona are incomplete, because the rostral part of the processus anterior of the malleus is always lacking due to damage of this extremely delicate structure. Our study shows that in perinatal stages of Leporidae the praearticulare develops a prominent processus internus that fits into a groove at the ventral side of the tegmen tympani; this "tongue and groove"-arrangement may act as a hinge. In adult stages, the rostral end of the praearticulare fuses synostotically with the medial process of the ectotympanic. Torsional strain produced by rotation around the axis of the middle ear ossicles at sound transmission must, therefore, be experienced by the extremely thin but highly elastic bony pedicle of the processus internus praearticularis. The free ending processus anterior of a late fetal Ochotona shows a short processus internus praearticularis, which does not articulate with the tegmen tympani. During postnatal development the middle ear of Ochotona becomes considerably remodelled: not only does excessive pneumatization of the tegmen tympani and tympanic cavity wall occur, but the short processus anterior is fused synostotically to a bone trabecula of the tegmen tympani meshwork. The thin and elastic bone bridges are not equivalent in Leporidae and Ochotonidae, that is, they must have evolved convergently. Fleischer's classification with Oryctolagus possessing a "freely mobile type" of middle ear ossicles cannot be supported by our observations. The same holds true for Ochotona, which does not represent a "freely mobile type" either. Thus, we suggest for the lagomorph middle ear ossicles a new category: the "bone elasticity type."

Morphological and morphometrical aspects of the auditory ossicles in goat (Capra hircus)

“…Thanks to its important integrative function, present‐day research for middle ear structure was reported for several species such as the chinese bamboo rat (Pleštilová, Hrouzková, Burda, & Šumbera, 2016), toad (Womack, Stynoski, Voyles, Coloma, & Hoke, 2018), rabbit (Guan et al., 2019), pig (Pracy, White, Mustafa, Smith, & Perry, 1998), miniature pigs (HaiJin et al., 2013), humans, (Arechvo et al., 2013; Isaacson, 2014; Luers & Hüttenbrink, 2016; Sawada, Nara, Fukui, Dodo, & Hirata, 2014; Stieger, Djeric, Kompis, Remonda, & Häusler, 2006; Whyte et al., 2001) other primates, moles (Mason, 2006), dog (Berghes, Parvu, Cucoanes, & Cuca, 2010; Ortug & Türkmenoğlu, 2005), Indian mangoose (Kamali, Gholami, Ahrari‐Khafi, Rasouli, & Shayegh, 2015), horse, cat, cow, rat, mouse (Amin & Tucker, 2006; Blanke, Aupperle, Seeger, Kubick, & Schusser, 2015; Botti, Secci, Ragionieri, Dessole, & Acone, 2006; Mohammadpour, 2010) or other extinct rodents (Lange, Stalleicken, & Burda, 2004), hamster, gerbil, New Zeeland rabbit (Kurtul, Cevik, Bozkurt, & Dursun, 2003), ostrich (Beșoluk et al., 2019; Keenan, Mears, & Skedros, 2017), degu (Argyle & Mason, 2008), weasel or chinchilla (Bergin, Vlajkovic, Bird, & Thorne, 2013; Carrasco, Maass, Dentone, Miranda, & Kukuljan, 2008; Charuta et al., 2011; Hoffstetter et al., 2011; Maier, Tröscher, & Ruf, 2018; Maravilla et al., 2011; Martonos et al., 2019; Rodrigues, Shinohara, Andreo, Buchaim, & Ahmed, 2012; Wang & Gan, 2016).…”

Morphological and morphometrical study of the auditory ossicles in chinchilla

“…Data related to the detailed anatomy of the auditory ossicles are relatively limited. A few elements were reported in case of birds (Mills, ), different rodents (Kerber & Sánchez‐Villagra, ; Kurtul et al, ; Lee, Park, Kang, & Choung, ; Li, Gao, Ding, & Salvi, ; Maier, Tröscher, & Ruf, ; Martins et al, ; Mohammadpour, , ; Şanlı, Sedat, & Oztürk, ), humans (García‐Real, Kass, Sturges, & Wisner, ; Isaacson, ), swine (Gurr, Kevenhörster, Stark, Pearson, & Dazert, ; Hoffstetter et al, ; Pracy, White, Mustafa, Smith, & Perry, ), miniature pigs (HaiJin et al, ), sheep (Ayres Seibel, Lavinsky, & Preto De Oliveira, ; Simaei, Soltanalinejad, Najafi, & Shalizar Jalali, ), chinchilla (Vrettakos, Dear, & Saunders, ; Wang & Gan, ), cat (Beck, Kilchling, & Meyer‐Lindenberg, ; Seifert et al, ), dog (Berghes, Parvu, Cucoanes, & Cuca, ) and wolf (Gürbüz et al, ), badger (Rozen‐Rechels, Peigné, Germain, & Ladevèze, ), horse (Blanke, Aupperle, Seeger, Kubick, & Schusser, ), donkey (Awal et al, ), common degu (32) or other subterranean cavimorphes (Argyle & Mason, ).…”

Anatomy of the Nasal and Auditory Regions of the Fossil Lagomorph Palaeolagus haydeni: Systematic and Evolutionary Implications

“…Terminology of the described structures follows Ekdale (2013Ekdale ( , 2016, Ruf (2014), Maier and Ruf (2014), and Maier et al (2018). The results concerning Palaeolagus haydeni are discussed in comparison to extant Lagomorpha based on data from literature (e.g., Ruf, 2014;Maier et al, 2018) and against the background of combined phylogeny from Matthee et al (2004), andMeng (2013). For grundplan reconstruction that allows defining all characters (apomorphic and plesiomorphic) of the last common ancestor of a respective taxon we follow the definition by Hennig (1984).…”

“…For grundplan reconstruction that allows defining all characters (apomorphic and plesiomorphic) of the last common ancestor of a respective taxon we follow the definition by Hennig (1984). The same scans of adult extant Lagomorpha included in the study on the auditory ossicles in Maier et al (2018) are used to discuss characters of the middle ear and the bony labyrinth.…”

“…However, recent studies on extant Lagomorpha revealed phylogenetically relevant characters of the nasal and ear regions. Ochotonidae and Leporidae can clearly be distinguished by specific characters of the turbinal skeleton and of the middle ear such as the pattern of the processus anterior and the processus praearticularis internus of the malleus (Ruf, 2014;Maier et al, 2018).…”