Evolutionary Anatomy and Phyletic Implication of the Extrinsic Cardiac Nervous System in the Philippine Tarsier (Tarsius syrichta, Primates) in Comparisons With Strepsirrhines and New World Monkeys

Abstract

To provide information on evolutionary morphological differences and similarities between Tarsiformes (tarsiers) and other primates (Strepsirrhini and Platyrrhini), we examined the previously undescribed extrinsic cardiac nervous system (ECNS) and surrounding structures in three Philippine tarsiers (Tarsius syrichta). We found that the complicated ECNS morphology shows little variation in contrast to significant anatomical diversity of the surrounding somatic structures in tarsiers as reported in our previous primate studies. Further, our comparative morphological data on the ECNS show the following aspects of evolutionary anatomical significance; (1) the traits of the general relationship between the superior cervical ganglion and the spinal nerves are common to the Tarsii and Strepsirrhini, (2) the traits of the general composition of the cervicothoracic ganglion, its communicating branches to spinal nerves, and its cardiac nerve are common to the Tarsii and Platyrrhini, and (3) the traits of the general relationship between the middle cervical ganglion and the spinal nerves and its cardiac nerve are common among Strepsirrhini, Tarsii, and Platyrrhini. Therefore, the general anatomical characteristics of the ECNS in tarsiers retain a primitive state for some traits and exhibit a derived state for others. These characteristics of the ECNS also reflect an evolutionary history without the modification and specialization as seen in the surrounding somatic structures. It may play a key role in unifying future studies on molecular phylogeny and updating evolutionary anatomical information. Anat Rec,

Anatomy of Shoulder Girdle Muscle Modifications and Walking Adaptation in the Scaly Chinese Pangolin (Manis Pentadactyla Pentadactyla: Pholidota) Compared with the Partially Osteoderm‐Clad Armadillos (Dasypodidae)

“…Various authors have given these additional levator scapularis muscles different names – such as atlantoscapularis (Bryant, ; Schön, ), occipitoscapularis (Woods, ;), rhomboideus occipitalis/capitis (Greene, ; Jouffroy, ), basiooccipital (Parsons, ; Hill, ), and omocervicalis (McKenzie, ), depending on their attachment sites. This altered levator scapularis muscle attachment to the spine of the scapula has been reported in Virginia opossum (Jenkins and Weijs, ), some rodents (Greene, ; Thorington et al, ) and almost all primates (Kawashima et al, 2007, , 2011, ; Kawashima and Thorington, ; Kawashima and Sato, ). However, we should note that these additional scapular muscles are normally innervated by the dorsal scapular nerve so they should be regarded as the accessory or additional levator spacularis muscles.…”

“…Therefore, our description of the brachial plexus and its branches in the pangolins is the first report in the literature. To date we have examined the brachial plexus in various mammals including unpublished data (Kawashima et al, ; Kawashima and Thorington, ; Kawashima and Sato, ; Yoshitomi et al, ). Our results suggest that the mammalian brachial plexus tends to maintain its segmental roots and branching patterns, and its evolutionary transformation by locomotive modes is less conspicuous than in the other somatic skeleton and muscles.…”

The relevance of the superior cervical ganglion for cardiac autonomic innervation in health and disease: a systematic review

“…The relation between the SCG and cardiac innervation has been studied in various species of nonhuman primates (arranged by primate evolutionary phylogeny): Lorisiformes (lorises and galagos) [ 29 ], tarsiers [ 30 ], New World Monkeys [ 31 ], Old World Monkeys (e.g., rhesus, macaque, and Taiwan monkey) [ 32 – 34 ], gibbons [ 35 ], and unspecified [ 36 ].…”

“…Most studies included subjects from both sexes [ 29 , 31 , 33 , 35 ], although the exact number per sex was sometimes not reported [ 36 ]. One study included only males, and one study did not report on the sex [ 30 , 32 ]. In case results were specified per sex, no evident differences existed [ 31 , 33 , 35 ].…”

“…In case results were specified per sex, no evident differences existed [ 31 , 33 , 35 ]. Both sides of the SCG were included in all studies, but the relevance of sidedness remains dubious, as some reported no differences [ 30 , 32 , 33 ], while others found a dominance of the left SCG over the right SCG, or reported that relevance of sidedness depended on the injected location of HRP [ 31 , 34 – 36 ]. No prenatal studies in the nonhuman primates investigating the connections between SCG and the heart were found.…”