MORPHOLOGY OF THE TONGUE APPARATUS OF C1R1DOPS ANNA (DREPANIDIDAE)

Ciridops possesses a tubular tongue with a fringed tip and lateral sides. Closure of the tube is by overlap of the lateral fringes.
The tongue skeleton possesses an elongated basihyale, parallel paraglossalia with broad, rounded posterior processes and a slight concavity on the dorsolateral surface of the ceratobranchiale.
All the tongue muscles could be described, although some had been damaged. The M. hypoglossus anterior is absent. The M. ceratoglossus and the M. hypoglossus obliquus are large, the latter muscle inserts completely on the basihyale. A newly discovered muscle, the M. thyreohyoideus superior, is described.
The glottal muscles are described, and their actions in opening and closing the glottis are outlined.
Comparison of Ciridops (Drepanidinae) and Loxops (Psittirostrinae) suggests that the Drepanididae are monophyletic. The closest resemblance in morphology of the tongue apparatus is with the cardueline finches, not with the "coerebids".     

Affinities of Carpospiza brachydactyla (Passeriformes; Passeridae)

The Passeridae are characterized by possessing a neomorphic preglossale bone in the tongue and a uniquely enlarged M. hypoglossus anterior forming part of the seed-cup used to orient and hold seeds in position when they are being husked. The pale rock finch (Carpospiza brachydactyla), which had been suggested in recent years to be allied to the Fringillidae rather than to the Passeridae, also possesses these unique derived features of the passerine finches and hence is clearly a member of the latter group. Further, the combination of the neomorphic preglossale bone and the large M. hypoglossus anterior provide strong support for the independent evolution of granivorous feeding in the Passeridae and against the placement of these birds with any members of the Ploceidae.Communicated by F. Bairlein     

The preglossale of Passer (Aves: Passeriformes)--a skeletal neomorph

A skeletal neomorph – the preglossale – is described from the tip of the tongue in Passer. This medial unpaired skeletal element is a dorsally open trough articulating with the anterior tips of the paraglossalia and supporting the heavy epidermal pad of the seed-cup. The large paired Mm. hypoglossus anterior originate from the posterior half of the preglossale and insert onto the anterior bodies of the paired paraglossalia; they serve to depress the anterior portion of the preglossale. A regular pattern of dermal papillae is present in the seed-cup; these are arranged in about 20 rows of six to 8 papillae per row. Each papilla contains a series of Merkel cells and associated nerve endings (touch receptors). The seed-cup serves to orient and hold the seed in place while it is being husked; the battery of tactile receptors provides information on the position of the seed on the tongue. The preglossale serves to support the seed-cup and to change its shape – the curvature of the dorsal surface – as it is depressed relative to the paraglossalia. The paraglossale and associated features of the seed-cup in Passer would provide a valuable preparation to study a diversity of problems such as developmental interactions between endomesodermal and ecto-mesenchymal skeletal features, the ontogenetical development of Merkel cells, and the sensory physiology of Merkel cells and their associated nerve endings as tactile corpuscles.     

Tongue evolution in lungless salamanders, family plethodontidae. III. Patterns of peripheral innervation

Innervation of the tongue and associated musculature in plethodontid salamanders was studied using Palmgren stained sectioned materials, fresh dissection, and whole mounts of experimental specimens treated with horseradish peroxidase (HRP). Species studied were chosen to represent modes of tongue projection recognized by Lombard and Wake ('77). Special attention was given to species of the genera Plethodon, Batrachoseps, Pseudoeurycea, and Hydromantes, but representatives of other genera were investigated. As expected we found that cranial nerves IX and X and spinal nerve 1 supplied the muscles involved in tongue movement. The peripheral courses of the nerves were traced, and both functionally related and phylogenetically determined routes were found. As relative projection length increases, the nerves supplying the tongue tip also increase in length. When the tongue is at rest the long nerves are stored in coils. The coil of ramus lingualis lies between the ceratobranchials, but that of ramus hypoglossus is more variable, although constant within a species. Ramus hypoglossus bifurcates into separate branches to tongue and anterior musculature of the floor of the mouth. In generalized, presumably primitive, modes the bifurcation and coiling are far anterior. In most of the tongue projection modes bifurcation is relatively posterior, but in one, bifurcation is anterior, but coiling is relatively posterior in position. The most unusual condition is in Hydromantes, in which bifurcation is relatively posterior and a coiled ramus hypoglossus joins a coiled ramus lingualis to form a unique, coiled common ramus to the tongue tip. Hydromantes has the greatest projection distance of any salamander.     

The osteology and phylogeny of the Hawaiian finch radiation (Fringillidae: Drepanidini), including extinct taxa

The monophyly and phylogeny of the adaptive radiation of Hawaiian finches (Fringillidae: Drepanidini; honeycreepers, auct.) were studied using parsimony analysis of comparative osteology, combined with Templeton (Wilcoxon signed‐ranks) tests of alternative phylogenetic hypotheses. Eighty‐four osteological characters were scored in 59 terminal taxa of drepanidines, including 24 fossil forms, and in 30 outgroup species. The optimal phylogenetic trees show considerable agreement, and some conflict, with independently derived ideas about drepanidine evolution. The monophyly of a large Hawaiian radiation was upheld, although one fossil taxon from Maui fell outside the drepanidine clade. The finch‐billed species were placed as basal drepanidine taxa, and continental cardueline finches (Carduelini) were identified as the radiation's closest outgroups. The study found anatomical as well as phylogenetic evidence that the radiation had a finch‐billed ancestor. The optimal trees identify the red‐and‐black plumage group as a clade, and suggest that the tubular tongue evolved only once in the radiation. Because comparative osteology provides too few characters to strongly support all the nodes of the tree, it was helpful to evaluate statistical support for alternative hypotheses about drepanidine relationships using the Templeton test. Among the alternatives that received significant statistical support are a relationship of the drepanidines with cardueline finches rather than with the Neotropical honeycreepers (Thraupini), classification of the controversial genera Paroreomyza and Melamprosops as drepanidines, and a secondary loss of the tubular tongue in Loxops mana. The hypothesis of monophyly for all the Hawaiian taxa in the study was not rejected statistically. The study provides a framework for incorporating morphological and palaeontological information in evolutionary studies of the Drepanidini. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141 , 207–255.     

Kinetics of tongue projection in Ambystoma tigrinum: Quantitative kinematics,muscle function,and evolutionary hypotheses

The projectile tongue of caudate amphibians has been studied from many perspectives, yet a quantitative kinetic model of tongue function has not yet been presented for generalized (nonplethodontid) terrestrial salamanders. The purposes of this paper are to describe quantitatively the kinnematics of the feeding mechanism and to present a kinetic model for the function of the tongue in the ambystomatid salamander Ambystoma tigrinum. Six kinematic variables were quantified from high-speed films of adult A. tigrinum feeding on land and in the water. Tongue protrusion reaches its maximum during peak gape, while peak tongue height is reached earlier, 15 ms after the mouth starts to open. Tongue kinematics change considerably during feeding in the water, and the tongue is not protruded past the plane of the gape. Electrical stimulation of the major tongue muscles showed that tongue projection in A. tigrinum is the combined result of activity in four muscles: the geniohyoideus, Subarcualis rectus 1, intermandibularis posterior, and interhyoideus. Stimulation of the Subarcualis rectus 1 alone does not cause tongue projection. The kinetic model produced from the kinematic and stimulation data involves both a dorsal vector (the resultant of the Subarcualis rectus 1, intermandibularis posterior, and interhyoideus) and a ventral vector (the geniohyoideus muscle), which sum to produce a resultant anterior vector that directs tongue motion out of the mouth and toward the prey. This model generates numerous testable predictions about tongue function and provides a mechanistic basis for the hypothesis that tongue projection in salamanders evolved from primitive intraoral manipulative action of the hyobranchial apparatus.     

Oropharyngeal morphology in the basal tortoise Manouria emys emys with comments on form and function of the testudinid tongue

In tetrapods, the ability to ingest food on land is based on certain morphological features of the oropharynx in general and the feeding apparatus in particular. Recent paleoecological studies imply that terrestrial feeding has evolved secondarily in turtles, so they had to meet the morphological oropharyngeal requirements independently to other amniotes. This study is designed to improve our limited knowledge about the oropharyngeal morphology of tortoises by analyzing in detail the oropharynx in Manouria emys emys. Special emphasis is placed on the form and function of the tongue. Even if Manouria is considered a basal member of the only terrestrial turtle clade and was hypothesized to have retained some features reflecting an aquatic ancestry, Manouria shows oropharyngeal characteristics found in more derived testudinids. Accordingly, the oropharyngeal cavity in Manouria is richly structured and the glands are large and complexly organized. The tongue is large and fleshy and bears numerous slender papillae lacking lingual muscles. The hyolingual skeleton is mainly cartilaginous, and the enlarged anterior elements support the tongue and provide insertion sides for the well‐developed lingual muscles, which show striking differences to other reptiles. We conclude that the oropharyngeal design in Manouria differs clearly from semiaquatic and aquatic turtles, as well as from other reptilian sauropsids. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc.     

Reversal of hypoglossal dominance in canaries following unilateral syringeal denervation

Summary The song of intact male canaries develops under the almost exclusive control of the left hypoglossus and left syringeal half. Section of the left hypoglossus or of its tracheosyringealis branch induces the right hypoglossus to assume a dominant control over vocal behavior. When this operation is done during the first two weeks after hatching the ensuing song is under sole right hypoglossal control; if done during the third and fourth week after hatching song develops under shared right-left hypoglossal control. In either case the quality of song is close to that of intact birds of comparable age. If the left hypoglossal innervation to the syrinx is cut when song development is already well under way (plastic song) or after stable adult song has been acquired, then the quality of song developed is markedly poorer than that of controls. From these observations we may conclude that: 1) Left or right hypoglossal dominance are not necessary for the production of normal canary song. 2) Soon after hatching either hypoglossus has the potential to assume a dominant role in song development. 3) The ability of the right hypoglossus to develop normal song decreases as birds master song under dominant left hypoglossal control. It is suggested that hypoglossal dominance and dominance reversal may provide convenient material to study neuronal changes related to the learning of new motor tasks.Abbreviations e.l. external labium - i.t.m. internal tympaniform membrane - ts tracheosyringealis Steven Green, Myron C. Baker and Timothy DeVoogd provided invaluable help on statistical analysis. Steven Green also read the text and made useful suggestions.     

Structure and function of the hyolingual system in Hynobius and its bearing on the evolution of prey capture in terrestrial salamanders

The Hynobiidae is generally regarded as the most phylogenetically basal and least derived extant family of terrestrial salamanders. As in the other families of terrestrial salamanders, prey capture in the Hynobiidae is accomplished by lingual prehension. In Hynobius, the prey capture system appears to be a mosaic of derived and primitive features. This, in conjunction with previous studies, suggests that the hyolingual systems of all families of terrestrial salamanders have evolved various degrees of specialization since the appearance of the common ancestral condition. We propose that the generalized feeding system for the extant terrestrial salamanders includes a hyolingual skeleton comprised of one basibranchial, one pair of radial or radial-like structures, two pairs of ceratobranchials, two pairs of epibranchials, one pair of ceratohyals, and one urohyal arranged in a configuration similar to that of Hynobius; a simple, sac-like secondary tongue pad; a lift and thrust system of tongue projection; a four-part gape cycle; and a forward head and body surge. Modifications to this general plan, previously described for the disparate families, include various changes in the size, shape, and definition of the tongue pad, changes in the specific types of structures and configurations in the anterior hyolingual skeleton, secondary ossification in the posterior hyolingual skeleton, the appearance of various protrusion, projection, and flipping systems for tongue protraction, simplification of the kinematic gape profile, and loss of the forward head and body surge. The evolutionary trends in these modifications have provided a rich data set from which much phylogenetic information has been inferred. © 1996 Wiley-Liss, Inc.     

REGIONAL VARIATION IN SWEET SUPPRESSION

Differences in the sweet‐blocking efficacy of 2‐(4‐methoxyphenoxy) propanoic acid (PMP) for different sweeteners (sucrose and aspartame) and for various exposure areas of the mouth were found. Twenty participants rated sweetener solutions with and without PMP for sweetness, sourness, saltiness, bitterness and umami for stimulation of anterior tongue, posterior tongue and whole‐mouth areas. For sweetness ratings, suppression was significant for all stimulation areas. In the presence of PMP, stimulation of the posterior tongue yielded significantly higher sweetness ratings than stimulation of the anterior tongue for aspartame but not for sucrose. Sourness and bitterness ratings were significantly higher for anterior tongue than posterior tongue stimulations for aspartame but not for sucrose. The increases in sourness ratings in the presence of PMP were likely because of the sour taste PMP has at the concentration used. Results imply a difference between the front and the back of the tongue in the mechanisms involved in the perception of sweetness.     

Gross morphology and topographical relationships of the hyobranchial apparatus and laryngeal cartilages in the ostrich (Struthio camelus)

The ostrich hyobranchial apparatus consists of the centrally positioned paraglossalia and basiurohyale and paired caudo‐lateral elements (horns), each consisting of the ceratobranchiale and epibranchiale. The paraglossalia lie within the tongue parenchyma and consist of paired, flat, caudo‐laterally directed cartilages joined rostrally. The basiurohyale forms a single dorso‐ventrally flattened unit composed of an octagonal‐shaped body from which extend rostral (the rostral process) and caudal (the urohyale) projections. The laryngeal skeleton consists of cricoid, procricoid and paired arytenoid cartilages. The large ring‐shaped cricoid cartilage displays a body and paired wings which articulate with each other and with the procricoid. The blunt, ossified, rostral projection of the cricoid and the scalloped nature of the arytenoid cartilages are unique to the ostrich. The procricoid is a single structure which links the paired arytenoids and wings of the cricoid. The hyobranchial apparatus is firmly attached to the tongue parenchyma and to the larynx and proximal trachea. In contrast to previous reports in this species, the horns of the hyobranchial apparatus are not related to the skull. Ossification of the body of the basihyale, the ceratobranchials and the rostral process and body of the cricoid cartilage of the larynx lends stability to these structures.     

Ultrastructure of the tongue and anterior process of the sublingual plica in four species of venomous snakes

The general histology and ultrastructure of the tongue and anterior process of the sublingual plica of four Taiwanese venomous snakes, the Chinese cobra (Naja naja atra), banded krait (Bungarus multicinctus), Taiwan habu (Trimeresurus mucrosquamatus), and bamboo snake (Trimeresurus stejnegeri stejnegeri) are described. The tongue fork exhibits a mid-dorsal invagination that broadens gradually toward its base. No mid-ventral invagination is observed. The epithelial cells on both dorsal and ventral aspects of the tongue fork have large and small microfacets, micropores and microvilli. The cell size, distribution pattern of the large microfacets, and the number of small microfacets present on both sides of the fork are essentially the same within a species, but vary among species. The function of these ultrastructures on the cell surface might be for the capture of chemical substances. The large microfacets are raised areas of the cell membrane, each with a pale granule contained within. The chemical nature of the pale granule is not yet known. The small pores surrounding the large microfacets are shallow hollows left after the release of the pale granules from the microfacets. The basic histological pattern of the tongue fork of these species is similar, being composed of a mucosal layer outside and dense musculature inside. No taste buds are discernible. The anterior processes are concave-like expansions of the anteriormost portions of the sublingual plicae. The oblique folds and micropapillae of this organ might be helpful for receiving the chemicals collected on the tongue, when the tongue makes contact with the elevated processes. The elevated processes may penetrate the ducts of Jacobson's organs to effect the final transfer.     

Morphology and evolution of the ectethmoid-mandibular articulation in the meliphagidae (Aves)

The ectethmoid-mandibular articulation in Melithreptus and Manorina (Meliphagidae: Aves) consists of the dorsal mandibular process fitting into and abutting against the ventral ectethmoid fossa; it forms a brace for the mandible. This articulation in Melithreptus is a typical diarthrosis with long folded capsular walls. The mandible, thus, has two separate articulations, each with a different axis of rotation. No other genus of Meliphagidae (except Ptiloprora) or any other avian family possesses a similar feature. The jaw and tongue musculature of Melithreptus are described. The two muscles opening the jaws are well developed, while those closing the jaws are small. The tongue muscles show no special developments. A large maxillary gland, presumably muscus secreting, covers the ventral surface of the jaw muscles. Its duct opens into the oral cavity just behind the tip of the upper jaw. The frilled tip of the tongue rests against the duct opening. The ectethmoid-mandibular articulation braces the adducted mandible against dorsoposteriorly directed forces. The mandible can be held closed without a compression force exerted by the mandible on the quadrate, permitting the bird to raise its upper jaw with greater ease and less loss of force. The tongue can be protruded through the slight gap between the jaws, moving against the duct opening and thus be coated with mucus. Presumably, these birds capture insects with their sticky tongue. Hence, the ectethmoid-mandibular articulation is an adaptation for this feeding method; it evolved independently in three genera of the Meliphagidae. The ectethmoid-mandibular articulation demonstrates that a bone can have two articulations with different axes of rotation, that the two articular halves can separate widely, and that articular cartilages can be flat and remain in contact over a large area. Its function suggests that the basitemporal articulation of the mandible found in many other birds has a similar function. And it demonstrates that in the evolution of the mammalian dentary-squamosal articulation, the new hinge did not have to lie on the same rotational axis as the existing quadrate-articular hinge.     

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

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.”     

Endocasts of Microsyops (Microsyopidae, Primates) and the evolution of the brain in primitive primates

We describe a virtual endocast produced from ultra high resolution X-ray computed tomography (CT) data for the microsyopid, Microsyops annectens (middle Eocene, Wyoming). It is the most complete and least distorted endocast known for a plesiadapiform primate and because of the relatively basal position of Microsyopidae, has particular importance to reconstructing primitive characteristics for Primates. Cranial capacity is estimated at 5.9 cm³, yielding encephalization quotients (EQ) of 0.26–0.39 (Jerison’s equation) and 0.32–0.52 (Eisenberg’s equation), depending on the body mass estimate. Even the lowest EQ estimate for M. annectens is higher than that for Plesiadapis cookei, while the range of estimates overlaps with that of Ignacius graybullianus and with the lower end of the range of estimates for fossil euprimates. As in other plesiadapiforms, the olfactory bulbs of M. annectens are large. The cerebrum does not extend onto the cerebellum or form a ventrally protruding temporal lobe with a clear temporal pole, suggesting less development of the visual sense and a greater emphasis on olfaction than in euprimates. Contrasts between the virtual endocast of M. annectens, and both a natural endocast of the same species and a partial endocast from the earlier-occurring Microsyops sp., cf. Microsyops elegans, suggest that the coverage of the caudal colliculi by the cerebrum evolved within the Microsyops lineage. This implies that microsyopids expanded their cerebra and perhaps evolved an improved visual sense independent of euprimates. With a growing body of data on the morphology of the brain in primitive primates, it is becoming clear that many of the characteristics of the brain common to euprimates evolved after the divergence of stem primates from other euarchontans and likely in parallel in different lineages. These new data suggest a different model for the ancestors of euprimates than has been assumed based on the anatomy of the brain in visually specialized diurnal tree shrews.     

Jaw muscles of new world squirrels

The jaw, suprahyoid, and extrinsic tongue muscles are described for eight species of New World squirrels, spanning more than an order of magnitude in body mass. Anatomical differences are discussed in the light of body size, natural history, and phylogeny. The relative sizes of different muscles, their orientations, and the shapes and positions of their areas of attachment vary but show few trends in relation to body size. The anatomical differences are likewise not readily explained by the mechanical requirements of the animals' diets, which are similar. The most marked anatomical differences occur in Sciurillus (the pygmy tree squirrel), as well as those genera—Glaucomys (the flying squirrel) and Tamias (the chipmunk)—that are taxonomically most distinct from the tree squirrels. sciurillus is noteworthy for its unusually small temporalis and an anterior deep masseter that is oriented to assist in retraction of the jaw. Tamias has a more vertically oriented temporalis and greater inclination in the anterior masseter muscles than the other squirrels, features that may be associated with its large diastema and relatively posteriorly situated cheek teeth, which in turn may relate to its having cheek pouches. Our results form a valuable database of information to be used in further studies of functional morphology and phylogeny. © 1995 Wiley-Liss, Inc.     

SEPERATION OF MALLOMONAS DUERRSCHMIDTIAE SP. NOV. FROM M. CRASSISQUAMA AND M. PSEUDOCORONATA: IMPLICATIONS FOR PALEOLIMNOLOGICAL RESEARCH1

A new species, Mallomonas duerrschmidtiae, with characteristics common to both Mallomonas crassisquama (Asmund) Fott and Mallomonas pseudocoronata Prescott, is described from acidic lakes low in specific conductance and total phosphorus concentration. Characteristics of scales, bristles and spines serve to separate the three taxa. The length and area of scales of M. duerrschmidtiae are significantly larger than those of M. crassisquama but smaller than those of M. pseudocoronata. Although the anterior submarginal ribs of scales of M. duerrschmidtiae may become extended to form short wings, the scales lack the large forward projecting anterior wings characteristic of scales of M. pseudocoronata. Features of the dome and junction between the arms of the V-rib and anterior submarginal ribs also serve to distinguish between the three species. Cells of M. duerrschmidtiae also possess long, smooth and thick spines on their posterior scales and lack helmet bristles. M. duerrschmidtiae has different maxima along pH, temperature, specific conductance, total phosphorus and seasonal gradients than either M. crassisquama or M. pseudocoronata. Discriminant analysis, based on nine morphological characters, was used to successfully classify body scales of the three species. The importance of M. duerrschmidtiae as a bioindicator in future lake monitoring and paleolimnological inference studies is discussed.