Journal of Morphology最新文献

{"title":"Male genitalia, hierarchical homology, and the anatomy of the bullet ant (Paraponera clavata; Hymenoptera, Formicidae)","authors":"Brendon E. Boudinot,&nbsp;Thomas van de Kamp,&nbsp;Patricia Peters,&nbsp;Katja Knöllinger","doi":"10.1002/jmor.21757","DOIUrl":"10.1002/jmor.21757","url":null,"abstract":"<p>The male genitalia of insects are among the most variable, complex, and informative character systems for evolutionary analysis and taxonomic purposes. Because of these general properties, many generations of systematists have struggled to develop a theory of homology and alignment of parts. This struggle continues to the present day, where fundamentally different models and nomenclatures for the male genitalia of Hymenoptera, for example, are applied. Here, we take a multimodal approach to digitalize and comprehensively document the genital skeletomuscular anatomy of the bullet ant (<i>Paraponera clavata</i>; Hymenoptera: Formicidae), including hand dissection, synchrotron radiation microcomputed tomography, microphotography, scanning electron microscopy, confocal laser scanning microscopy, and 3D-printing. Through this work, we generate several new concepts for the structure and form of the male genitalia of Hymenoptera, such as for the endophallic sclerite (=fibula ducti), which we were able to evaluate in detail for the first time for any species. Based on this phenomic anatomical study and comparison with other Holometabola and Hexapoda, we reconsider the homologies of insect genitalia more broadly, and propose a series of clarifications in support of the penis-gonopod theory of male genital identity. Specifically, we use the male genitalia of <i>Paraponera</i> and insects more broadly as an empirical case for hierarchical homology by applying and refining the 5-category classification of serial homologs from DiFrisco et al. (2023) (DLW23) to all of our formalized concepts. Through this, we find that: (1) geometry is a critical attribute to account for in ontology, especially as all individually identifiable attributes are positionally indexed hence can be recognized as homomorphic; (2) the definition of “structure” proposed by DLW23 is difficult to apply, and likely heterogeneous; and (3) formative elements, or spatially defined foldings or in- or evaginations of the epidermis and cuticle, are an important yet overlooked class of homomorphs. We propose a morphogenetic model for male and female insect genitalia, and a model analogous to gene-tree species-tree mappings for the hierarchical homology of male genitalia specifically. For all of the structures evaluated in the present study, we provide 3D-printable models – with and without musculature, and in various states of digital dissection – to facilitate the development of a tactile understanding. Our treatment of the male genitalia of <i>P. clavata</i> serves as a basic template for future phenomic studies of male insect genitalia, which will be substantially improved with the development of automation and collections-based data processing pipelines, that is, collectomics. The Hymenoptera Anatomy Ontology will be a critical resource to include in this effort, and in best practice concepts should be linked.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21757","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First soft body morphological data on the tracemaker of the endolithic bryozoan trace fossil Terebripora ramosa d'Orbigny, 1842","authors":"Sebastian H. Decker,&nbsp;Felipe Aguilera,&nbsp;Ahmed J. Saadi,&nbsp;Thomas Schwaha","doi":"10.1002/jmor.21770","DOIUrl":"10.1002/jmor.21770","url":null,"abstract":"<p>Terebriporidae is one of the four extant endolithic ctenostome bryozoan families, with colonies immersed into carbonate substrates like molluscan shells. This monogeneric family comprises 17 species, with 11 extant and 6 fossil species. It is currently considered closely related to vesicularioid ctenostomes, a group characterized by colonies interconnected by polymorphic stolons and a distinct gizzard as part of their digestive systems. However, confusion persists regarding the correct species identities and affiliations of many terebriporid species, and even the description of the entire family is based solely on a few external features of their boring traces, rendering the family an ichnotaxon (trace fossil). Our molecular analysis does not support a vesicularioid affinity, but corroborate a close relationship to <i>Immergentia</i>, another genus of boring bryozoans. Consequently, this study aims to untangle the systematic confusion surrounding Terebriporidae by examining the tracemaker of the type species of the family, <i>Terebripora ramosa</i> from Chile, and investigating its morphology and histology using modern techniques. The current analysis could not confirm typical vesicularioid characters such as a gizzard or true polymorphic stolons. Instead, all characters point towards a closer relationship to Immergentiidae as suggested by a recent molecular phylogeny. In fact, these two taxa share several characters such as cystid appendages and duplicature bands, and appear closely related, with the only difference being a characteristic vane with tubulets present in the tracemaker of <i>T. ramosa</i>. The sister-group relationship of the tracemaker and the genus <i>Immergentia</i> infers that these borers share a common boring ancestor, but also emphasizes that additional species from the ichnogenus <i>Terebripora</i> need to be studied for more clarity.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21770","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142055832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The mammary hair of Monodelphis domestica and homology of the mammary pilosebacous unit","authors":"Daniel J. Stadtmauer,&nbsp;Günter P. Wagner","doi":"10.1002/jmor.21769","DOIUrl":"10.1002/jmor.21769","url":null,"abstract":"<p>The unitary mammary gland is a synapomorphy of therian mammals and is thought to have evolved from the pilosebaceous organ in the mammalian stem lineage from which the lactogenic patch of monotremes is also derived. One of the key lines of evidence for the homology of the nipple and the lactogenic patch is that marsupials have retained a transient hair associated with developing mammary glands. However, these structures have not been documented since the early 20th-century drawings of Ernst Bresslau. In this study, we examine the developing mammary organs of <i>Monodelphis domestica</i> and document the presence of mammary hairs in 12-week-old females, as well as their absence after 18 weeks of age. Histochemical staining for cystine confirms the structures as keratinized hairs. Milk ducts of both juvenile and adult nipples show a division between KRT18⁺ luminal epithelium and KRT14⁺ ACTA2⁺ myoepithelium. These patterns match those in eutherians and suggest a conserved ductal morphology and mechanism of milk expulsion. Finally, PTHLH, a peptide hormone which promotes homeotic transformation of hairy skin into hairless nipples in the mouse, was detected in the <i>Monodelphis</i> milk duct during the mammary hair stage, suggesting that the mutual exclusivity of “hairless nipple” and “hair” organ identity is derived in eutherian mammals. These results reveal shared characteristics of the <i>M. domestica</i> nipple with both the eutherian nipple and the pilosebaceous organ, consistent with the evolutionary derivation of the mammary gland from an ancestral hair organ via developmental individualization of pilosebaceous and mammary identities.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21769","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142073097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chewing shrews: Examining the morphology and function of the masticatory musculature in Soricidae via diffusible iodine-based contrast-enhanced computed tomography","authors":"Sebastian D. V. Pommerening,&nbsp;Thomas Martin","doi":"10.1002/jmor.21761","DOIUrl":"10.1002/jmor.21761","url":null,"abstract":"<p>Essential for sustaining a high metabolic rate is the efficient fragmentation of food, which is determined by molar morphology and the movement of the jaw. The latter is related to the jaw morphology and the arrangement of the masticatory muscles. Soricid jaw apparatuses are unique among mammals, as the articulation facet on the condylar process is separated into a dorsal and a ventral part, which has often been linked to more differentiated jaw motions. Soricidae also possess a remarkably elongated angular process. However, the precise function of the unique morphology of soricid jaw apparatuses has not been fully understood yet. By digitally reconstructing the masticatory musculature via the diffusible iodine-based contrast-enhanced computed tomography technique, we show how the unique jaw morphology is reflected in the spatial organization as well as the inner architecture and respective fascicle orientations of the muscles. From the lines of action of the <i>m. masseter</i> and the <i>m. pterygoideus internus</i>, both muscles inserting on the lateral and medial side of the angular process, respectively, we infer that the angular process is substantial for roll and yaw rotations of the mandible. The <i>m. masseter</i> is subdivided into four and the <i>m. pterygoideus internus</i> into five subunits, each exhibiting a slightly different line of action and torque. This enables Soricidae to adjust and adapt these rotational movements according to the properties of the ingested food, allowing for more efficient fragmentation. Additionally, those guided rotational motions allow for precise occlusion despite tooth wear. The temporalis is the largest of the adductor muscles and is mainly responsible for exerting the bite force. Overall, the unique jaw bone morphology in conjunction with the complex muscle arrangement may contribute towards a more efficient energy gain and the maintenance of a high metabolic rate, which is crucial for small-bodied mammals such as shrews.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21761","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142046827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gastrotheca Fitzinger, 1843 tadpole morphology: Larval cranium description and its evolutionary implications (Amphibia: Anura: Hemiphractidae)","authors":"Manuella Folly,&nbsp;Lucas C. Amaral,&nbsp;Luiz F. L. da Silveira,&nbsp;Sergio P. de Carvalho-e-Silva,&nbsp;Pedro Henrique dos Santos Dias","doi":"10.1002/jmor.21766","DOIUrl":"10.1002/jmor.21766","url":null,"abstract":"<p>Hemiphractids have a singular mode of reproduction that involves maternal care. The Andean-endemic <i>Gastrotheca marsupiata</i> species group includes direct-developing and tadpole-bearing species, the latter trait being unique among <i>Gastrotheca</i>. Larval morphology has proven to be a valuable source of evidence to understand the taxonomy and evolution of frogs but remains understudied in Hemiphractids. Herein, we redescribe the larval cranium of <i>G. espeletia</i>, <i>G. gracilis</i>, <i>G. marsupiata</i>, <i>G. peruana</i>, <i>G. pseustes</i>, and <i>G. riobambae</i>, and describe those of <i>G. aureomaculata</i>, <i>G. chrysosticta</i>, <i>G. litonedis</i>, <i>G. monticola</i> and <i>G. psychrophila</i>. Additionally, based on the data gathered, we explore their phylogenetic significance, expanding the knowledge regarding <i>Gastrotheca</i> larval internal morphology. We suggest that the presence of the posterolateral process of crista parotica, the concave palatoquadrate, the quadratoorbital commissure, and the proximal commissures II and III are putative synapomorphies for <i>Gastrotheca</i>. Furthermore, we suggest the long pseudopterygoid process as a putative synapomorphy for Hemiphractyidae.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142017753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Patterns of dermal denticle loss in sharks","authors":"Michael A. Fath,&nbsp;Greta Wong,&nbsp;Chloé-Rose Colombero,&nbsp;Molly K. Gabler-Smith,&nbsp;George V. Lauder,&nbsp;Dylan K. Wainwright","doi":"10.1002/jmor.21764","DOIUrl":"https://doi.org/10.1002/jmor.21764","url":null,"abstract":"<p>As they grow, sharks both replace lost denticles and proliferate the number of denticles by developing new (de novo) denticles without prior denticle shedding. The loss and replacement of denticles has potential impacts on the energetic cost of maintaining the skin surface, the biomechanical functions of shark skin, as well as our ability to predict shark abundance from fossil denticle occurrence in sediment cores. Here, we seek to better understand patterns of denticle loss and to show how denticles are being replaced in mature sharks. We illustrate shark skin surfaces with missing denticles and quantify both within-species and between-species patterns of missing denticles using images from across regions of the body for two species and images at similar body regions for 16 species of sharks. Generally, sharks are missing similar numbers of denticles (0%–6%) between species and regions. However, there are exceptions: in the smooth dogfish, the nose region is missing significantly more denticles than most posterior-body and fin regions, and the common thresher shark is missing significantly more denticles than the smooth dogfish, leopard shark, angel shark, bonnethead, and gulper shark. Denticle regrowth starts with crown development and mineralization beneath the epidermis, followed by eruption of the crown, and finally the mineralization of the root. The pulp cavity of replacement denticles is initially large and surrounded by a thin shell of enameloid upon eruption of the denticle. After eruption of the denticle, the deposition of dentine continues internally after the denticle reaches its final position. Replacement of missing denticles, representing less than 6% of the skin surface at any one time, may not compromise hydrodynamic function, but by constantly updating the skin surface throughout life, sharks may reduce surface fouling and maintain a functional complex skin surface by repairing local damage to individual denticles.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21764","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142013663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrastructure of the extraordinary pedal gland in Asplanchna aff. herricki (Rotifera: Monogononta)","authors":"Rick Hochberg,&nbsp;Robert L. Wallace,&nbsp;Elizabeth J. Walsh,&nbsp;Thiago Q. Araújo","doi":"10.1002/jmor.21765","DOIUrl":"https://doi.org/10.1002/jmor.21765","url":null,"abstract":"<p>Rotifers possess complex morphologies despite their microscopic size and simple appearance. Part of this complexity is hidden in the structure of their organs, which may be cellular or syncytial. Surprisingly, organs that are cellular in one taxon can be syncytial in another. Pedal glands are widespread across Rotifera and function in substrate attachment and/or egg brooding. These glands are normally absent in <i>Asplanchna</i>, which lack feet and toes that function as outlets for pedal glandular secretions in other rotifers. Here, we describe the ultrastructure of a pedal gland that is singular and syncytial in <i>Asplanchna</i> aff. <i>herricki</i>, but is normally paired and cellular in all other rotifers. <i>Asplanchna</i> aff. <i>herricki</i> has a single large pedal gland that is active and secretory; it has a bipartite, binucleate, syncytial body and a cytosol filled with rough endoplasmic reticulum, Golgi, and several types of secretory vesicles. The most abundant vesicle type is large and contains a spherical electron-dense secretion that appears to be produced through homotypic fusion of condensing vesicles produced by the Golgi. The vesicles appear to undergo a phase transition from condensed to decondensed along their pathway toward the gland lumen. Decondensation changes the contents to a mucin-like matrix that is eventually exocytosed in a “kiss-and-run” fashion with the plasma membrane of the gland lumen. Exocytosed mucus enters the gland lumen and exits through an epithelial duct that is an extension of the syncytial integument. This results in mucus that extends from the rotifer as a long string as the animal swims through the water. The function of this mucus is unknown, but we speculate it may function in temporary attachment, prey capture, or floatation.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 9","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21765","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141994209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of the cranial lateral line system of Brook Trout, Salvelinus fontinalis (Teleostei: Salmonidae): Evolutionary and ecological implications","authors":"Aubree E. Jones,&nbsp;Pedro P. Rizzato,&nbsp;Jacqueline F. Webb","doi":"10.1002/jmor.21754","DOIUrl":"10.1002/jmor.21754","url":null,"abstract":"<p>The mechanosensory lateral line (LL) system of salmonid fishes has been the focus of comparative morphological studies and behavioral and physiological analyses of flow sensing capabilities, but its morphology and development have not been studied in detail in any one species. Here, we describe the post-embryonic development of the cranial LL system in Brook Trout, <i>Salvelinus fontinalis</i>, using vital fluorescent staining (4-Di-2-ASP), scanning electron microscopy, µCT, and clearing and staining to visualize neuromasts and the process of cranial LL canal morphogenesis. We examined the relationship between the timing of LL development, the prolonged life history of salmonids, and potential ecological implications. The LL system is composed of seven canals containing canal neuromasts (CNs) and four lines of superficial neuromasts (SNs) on the skin. CNs and SNs increase in number and size during the alevin (larval) stage. CN number stabilizes as canal morphogenesis commences, but SN number increases well into the parr (juvenile) stage. CNs become larger and more elongated than SNs, but the relative area occupied by sensory hair cells decreases during ontogeny in both types of neuromasts. Neuromast-centered canal morphogenesis starts in alevins (yolk sac larvae), as they swim up into the water column from their gravel nests (~4 months post-fertilization), after which yolk sac absorption is completed and exogenous feeding begins. Canal morphogenesis proceeds asynchronously within and among canal series and is not complete until ~8 months post-fertilization (the parr stage). Three characters in the LL system and associated dermal bones were used to identify their homologs in other actinopterygians and to consider the evolution of LL canal reduction, thus demonstrating the value of salmonids for the study of LL evolution. The prolonged life history of Brook Trout and the onset of canal morphogenesis at swim-up are predicted to have implications for neuromast function at these critical behavioral and ecological transitions.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 8","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141971312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative anatomy of siphons in tellinoidean clams (Bivalvia, Tellinoidea)","authors":"Alan R. Batistão,&nbsp;Jorge A. Audino,&nbsp;Flávio D. Passos","doi":"10.1002/jmor.21762","DOIUrl":"10.1002/jmor.21762","url":null,"abstract":"<p>Siphons are tubular organs formed by fusion and posterior extension of the marginal mantle folds. They are supposed to have performed key roles in the evolution of bivalves by enabling these animals to occupy several ecological niches. However, anatomical details of these organs are scarce for one of the most diverse lineages of tropical bivalves, the superfamily Tellinoidea. We investigated the siphonal morphology of 15 species, sampling five tellinoidean families, by integrating scanning electron microscopy, confocal microscopy, and histology. The siphons revealed variations in length, pigmentation, tentacles, papillae, and number of nerve cords. Due to the presence of sensorial structures, such as papillae and tentacles, we reclassify the siphons of Tellinoidea from type A to A+. Additional anatomical patterns were identified at family and genus levels. For example, the incurrent siphon shorter than the excurrent and 24 tentacles are putative synapomorphies of Donacidae. We also highlight shared siphonal traits between Donacidae and Solecurtidae as well as between Semelidae and Tellinidae. In addition, our data support the idea of Psammobiidae as a paraphyletic lineage. Overall, we provide an extensive comparative data set on siphonal traits with significant relevance for bivalve taxonomy, functional anatomy, and evolutionary investigations.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 8","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141916986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How anatomy influences measurements of snakes","authors":"David Cundall,&nbsp;Alexandra Deufel,&nbsp;Abigail Pattishall","doi":"10.1002/jmor.21758","DOIUrl":"10.1002/jmor.21758","url":null,"abstract":"<p>Anatomy compromises the precision and accuracy of measurements made of the body length and head size of live snakes. Body measures (snout-vent length, SVL) incorporate many synovial intervertebral joints, each allowing flexion and limited extension and compression. Radiographs of the trunk in 14 phylogenetically diverse species in resting and stretched conditions combined with dissections and histological analysis of intervertebral joints show that the synovial nature of these joints underlies the variance in SVL measures. Similarly, the ubiquity and variety of viscoelastic tissues connecting mobile snout and jaw elements of alethinophidian snakes underlie variances in length and width measures of the head. For the overall size of the head and jaw apparatus, the part that can be most easily and relatively precisely measured for many snakes is the mandible because it has only one mobile joint. As to accuracy, the anatomy of intervertebral and cranial joints supports the hypothesis that in living snakes, the head and trunk have no exact size.</p>","PeriodicalId":16528,"journal":{"name":"Journal of Morphology","volume":"285 8","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jmor.21758","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141902018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}