Richard Carter

• PhD
• Professor (Assistant) at East Tennessee State University

Comparative analysis of nonflight morphologies can give important insight into the early ancestral origin of bats by revealing locomotor adaptations that may have predated wings. Because the scapula of bats is not directly involved in flight mechanics but does retain a primary role in walking and climbing, morphological analysis may help resolve if...

The external ear in eutherian mammals is composed of the annular, auricular (pinna), and scutellar cartilages. The latter extends between the pinnae, across the top of the head, and lies at the intersection of numerous auricular muscles and is thought to be a sesamoid element. In bats, this scutulum consists of two distinct regions, (1) a thin squa...

Most of over 1400 extant bat species produce high-frequency pulses with their larynx for echolocation. However, the debate about the evolutionary origin of laryngeal echolocation in bats remains unresolved. The morphology of the larynx is known to reflect vocal adaptation and thus can potentially help in resolving this controversy. However, the mor...

Synopsis The hyoid apparatus in laryngeally echolocating bats is unique as it forms a mechanical connection between the larynx and auditory bullae, which has been hypothesized to transfer the outgoing echolocation call to the middle ear during call emission. Previous finite element modeling (FEM) found that hyoid-borne sound can reach the bulla at...

Laryngeal echolocation in bats could have evolved following two scenarios: a single origin from a common ancestor or an independent acquisition inside the two clades Yinpterochiroptera and Yangochiroptera. Later, some members of Yinpterochiroptera possibly lost their ability to echolocate. In bats, the larynx produces vocalizations for communicatio...

The morphology of the stylohyal-tympanic bone articulation found in laryngeally echolocating bats is highly indicative of a function associated with signal production. One untested hypothesis is that this morphology allows the transfer of a sound signal from the larynx to the tympanic bones (auditory bulla) via the hyoid apparatus during signal pro...

The synchronization of flight mechanics with respiration and echolocation call emission by bats, while economizing these behaviors, presumably puts compressive loads on the cartilaginous rings that hold open the respiratory tract. Previous work has shown that during postnatal development of Artibeus jamaicensis (Phyllostomidae), the onset of adult...

How echolocation and flight evolved in modern day bats is a compelling and largely unanswered question in biology. As laryngeal echolocation in bats is typified by a bony connection between the larynx and the auditory bulla via the hyoid apparatus, we developed an evolutionary‐developmental model of the hyoid to test hypotheses regarding the evolut...

Understandably, most locomotor analyses of bats have focused on flight mechanics and behaviors. However, we investigated nonflight locomotion in an effort to glean deeper insights into the evolutionary history of bats. We used high-speed video (300 Hz) to film and compare walking and climbing mechanics and kinematics between several species of the...

Microchiropteran, Myotis thysanodes (Vespertilionidae), free-climbing. Note initiation of climb using forelimb, relatively limited extension of the humerus to positions below the shoulder plane, relatively limited abduction and protraction of the hindlimbs, and the use of a basic contralateral gait with 3 points of contact. Filmed at 300 Hz. (MP4)

Megachiropteran Pteropus hypomelanus (Pteropodidae) moving on the ground. Note ipsilateral movement of limbs with most propulsion coming from the hindlimbs. This individual also appears to be lifting its elongated thumb claws to avoid contact with the ground. Filmed at 300 Hz. (WMV)

Megachiropteran Pteropus pumilus (Pteropodidae)using its thumb claws to pull itself along the ground. Note the lack of hindlimb employment. Filmed at 300 Hz. (WMV)

Microchiropteran Eptesicus fuscus (Vespertilionidae) walking on a platform. Note the contralateral gait which affords stability at slow speeds as observed in basic tetrapods. Filmed at 300 Hz. (WMV)

Megachiropteran Eidolon helvum (Pteropodidae) free-climbing. Notice initiation of climb using rear-limb, ability to extend the humerus past the should plane, ability to abduct and protract the hindlimbs placing the hind foot near the head, and ipsilateral gait with only 1–2 points of contact. Filmed at 300 Hz. (AVI)

The evolutionary sequence of events that led to flight and echolocation in bats is a compelling question in biology. Fundamentally lacking from this discussion is the ontogeny of how these two systems become functionally integrated producing an evolutionary developmental model. We build such a model by integrating growth and development of the coch...

The production of echolocation calls in bats along with forces produced by contraction of thoracic musculature used in flight presumably puts relatively high mechanical loads on the lower respiratory tract (LRT). Thus, there are likely adaptations to prevent collapse or distortion of the bronchial tree and trachea during flight in echolocating bats...

Recent evidence has shown that the developmental emergence of echolocation calls in young bats follow an independent developmental pathway from other vocalizations and that adult-like echolocation call structure significantly precedes flight ability. These data in combination with new insights into the echolocation ability of some shrews suggest th...

Echolocating bats have adaptations of the larynx such as hypertrophied intrinsic musculature and calcified or ossified cartilages to support sonar emission. We examined growth and development of the larynx relative to developing flight ability in Jamaican fruit bats to assess how changes in sonar production are coordinated with the onset of flight...

A long-standing question in bat biology is if the evolution of echolocation and flight are associated or if they evolved independently, and if so, which evolved first. We seek to use ontogeny as a surrogate for understanding linkages between flight evolution and echolocation in bats. To do this we quantify the onset of recognizable sonar calls in n...