Table 3.
Mandibular muscles of adults of representative sarcopterygian taxa. The nomenclature of the muscles shown in bold follows that of the present work, "ad. mand." meaning adductor mandibulae. In order to facilitate comparisons, in some cases certain names often used by other authors to designate a certain muscle/bundle are given in front of that muscle/bundle. Data compiled from evidence provided by developmental biology, comparative anatomy, experimental embryology and molecular biology, innervation and phylogeny (for more details, see text).
| Probable plesiomorphic osteichthyan condition | Actinistia: Latimeria chalumnae (Coelacanth) | Dipnoi: Lepidosiren paradoxa (South American lungfish) | Amphibia: Ambystoma ordinarium (Michoacan stream salamander) | Reptilia: Timon lepidus (Ocellated lizard) | Mammalia: Rattus norvegicus (Norway rat) | Mammalia: Homo sapiens (Human) |
| Intermandibularis posterior (*see Table 2) | Intermandibularis posterior | Intermandibularis | Intermandibularis posterior | Intermandibularis posterior | Mylohyoideus (*mylohyoideus and digastricus anterior of rats derived from intermandibularis posterior, see e.g. Jarvik [53]) | Mylohyoideus |
| --- | --- | --- | --- | --- | Digastricus anterior (*see cell above) | Digastricus anterior |
| Intermandibularis anterior (*see Table 2) | Intermandibularis anterior | ----- | Intermandibularis anterior | Intermandibularis anterior | Intermandibularis anterior (transversus mandibularis of Greene [83]) | --- |
| Ad. mand. A3' | Ad. mand. A3' (ad. mand. 'moyen' of e.g. Millot and Anthony [24]) | Ad. mand. A3' (ad. mand. anterior of e.g. Bemis and Lauder [50]) | Ad. mand. A3' (pseudotemporalis posterior of e.g. Iordansky [73]) | Ad. mand. A3' (pseudotemporalis superficialis of e.g. Abdala and Moro [74]) | --- (*but see below) | --- (*but see below) |
| Ad. mand. A3" | Ad. mand. A3" (ad. man. 'profond' of e.g. Millot and Anthony [24]) | ----- | Ad. mand. A3" (pseudotemporalis anterior of e.g. Iordansky [73]) | Ad. mand. A3" (pseudotemporalis profundus of e.g. Abdala and Moro [74]) | --- (*but see below) | --- (*but see below) |
| ----- | ----- | ----- | ----- | Pterygomandibularis (*seemingly derived from mesial portion of ad. mand.) | --- (*but see below) | --- (*but see below) |
| --- | --- | --- | --- | --- | Pterygoideus medialis (*derived from mesial portion of ad. mand. of other tetrapods; seemingly corresponding to A3'/A3" and/or pterygomandibularis of e.g. lizards: see e.g. Saban [79]) | Pterygoideus medialis |
| Ad. mand. A2 | Ad. mand. A2 (ad. mand. 'superficiel' of e.g. Millot and Anthony [24]) | Ad. mand. A2 (part of ad. mand. posterior of e.g. Bemis and Lauder [50]) | Ad. mand. A2 (ad. mand. externus of e.g. Iordansky [73]) | Ad. mand. A2 (ad. mand. externus of e.g. Abdala and Moro [74]) | Masseter (*masseter, pterygoideus lateralis and temporalis of mammals seemingly derived from lateral, and eventually also medial, portions of ad. mand. of other tetrapods [12, 46, 79, 80]) | Masseter |
| --- | --- | --- | --- | --- | Temporalis (*see cell above) | Temporalis |
| --- | --- | --- | --- | --- | Pterygoideus lateralis (*see cell above) | Pterygoideus lateralis |
| ----- | ----- | Ad. mand. A2-PVM (part of ad. mand. posterior of e.g. Bemis and Lauder [50]) | Ad. mand. A2-PVM (ad. mand. posterior of e.g. Iordansky [73]) | Ad. mand. A2-PVM (ad. mand. posterior of e.g. Abdala and Moro [74]) | Tensor veli palatini (*tensor veli palatini and tensor tympani of mammals seemingly derived from ad. mand. A2-PVM of other tetrapods [12, 79]) | Tensor veli palatini |
| --- | --- | --- | --- | --- | Tensor tympani (*see cell above) | Tensor tympani |
| ----- | ----- | Retractor anguli oris (*seemingly derived from lateral portion of ad. mand.) | ----- | ----- | --- | --- |
| ----- | ----- | ----- | ----- | Levator anguli oris (*present, somewhat mixed with A2; seemingly derived from lateral portion of ad. mand, it may eventually be derived/modified from the retractor anguli oris, or at least from the portion of the mandibular muscle plate originating that muscle in other osteichthyan taxa) | --- | --- |
| Ad. mand. Aω | Ad. mand. Aω (intramandibular adductor of e.g. Lauder [75]) | ----- | ----- | Ad. mand. Aω (*in Timon the ad. mand. has an anteroventral section that is lodged in the 'adductor fossa' and that is very similar to the Aω of other osteichthyan taxa: is this section homologous to the Aω of those taxa? [36]) | --- | --- |
| Levator arcus palatini | Levator arcus palatini | ----- | ----- | Levator pterygoidei (*it may well be derived/modified from the levator arcus palatini, or at least from the portion of the mandibular muscle plate originating that muscle in other osteichthyan taxa) | --- | --- |
| ----- | ----- | ----- | ----- | Protractor pterygoidei (*same as cell above) | --- | --- |