摘要:

Evidence from outgroups, ontogeny, neontology, and fossils is used to distinguish primitive and derived character states for the major components of the eutherian stapedial artery in 17 modern orders. Derived states support the following higher‐level phylogenetic hypotheses: (1) Microchiroptera and Megachiroptera are monophyletic+ADs‐ and (2) within Ungulata, Tubulidentata is the outgroup to the remaining modern orders, followed in succession by Artiodactyla and then Cetacea. Three branches of the stapedial artery, the a. diploetica magna, ramus temporalis, and ramus posterior, all but neglected in previous syntheses, are shown to be primitive for Eutheria and Amni

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1987.tb01725.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Adult and larval Otophryne robusta‐ were collected in Colombia, South America. Although this genus has been assigned to the family Microhylidae, a variety of both adult and larval features distinguish it from all other microhylids. The adult is a diurnally active leaf mimic with complex agonistic behaviours and vocalizations. It tends to walk rather than hop, and does not burrow in captivity. The larva is unique in having minute, dagger‐like, keratinized teeth and a sinistral spiracle at the tip of a long tube. The mature larva lives shallowly buried in sand at the bottom of clear, shallow streams. The anatomy of the tadpole was examined for clues to how it burrows into and survives in sand, as well as to the correct phylogenetic association of the genus. Internally, the tadpole is most similar to microhylid tadpoles and has a wealth of oral features (e.g. unperforated internal nares, branchial food traps arranged in crescentic organs, ventral velum divided on the midline, glottis located rostral to the free edge of the ventral velum, large gill filters etc.) that characterize that family. Most, if not all, of the unique features of theOtophrynelarva can be associated with its fossorial existence. The arrangement of the muscles suggest that it can actively raise and lower its snout during burrowing and possibly dorsiflex its head on its vertebral column. Although the larval teeth first suggest carnivory, many features indicate that maerophagy is not possible. Stomach contents include a variety of bacteria and micro‐organisms, but no fragments of macroscopic animals. We conclude that theOtophrynetadpole is a microphagous suspension feeder and its teeth are more important for keeping sand grains out of its mouth than for grasping prey. Since theO. robustalarva does not burrow deeply, the tip of its spiracular tube probably extends upward above the sandy bottom and into the current. In this position pressure would be lower at the spiracle than at the mouth and a current could be passively drawn (by the Bernoulli effect) through the oral cavity for feeding and respiration. If this is correct then theOtophrynelarva is the first fossorial vertebrate known to passively filter‐feed. All features of the tadpole, except the keratinized teeth and sinistral spiracle, indicate an affinity ofOtophryne‐/i with South American microhylids. The tadpole and adult are, however, so unusual as to warrant subfamilial status+ADs‐ we propose the subfamily Otophryninac for this mono

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1987.tb01726.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Mechanical theory is used to erect a paradigm predicting the manipulations used by carnivorous aquatic amphibians, reptiles, birds and mammals to catch, subdue, process and swallow their prey. These predictions are confirmed by observational evidence. Most aquatic predatory tetrapods use long, prehensile tooth‐armed jaws as pincer jaws to snap shut onto the prey and catch and kill it, although some use the flexibility of long necks in spear fishing and some odontocetes may stun prey with sonar. Most do not have cutting or nipping dentitions as these cannot be used on prey which is freely floating. They use caniniform dentition to hold and kill prey, or in some cases crushing dentition to break open hard‐shelled prey. They dismember prey by dynamic loading, snatching bites so quickly that the prey tears. They use shake feeding, shaking the prey apart from side to side above the water. If the prey is too large to lift above the water they use twist feeding, twisting pieces off. Small pieces are easily swallowed but larger pieces are held above the water and swallowed by tilting the head back in gravity feeding, or by jerking the head back and forth in incrtial feeding. Some animals use mobile jaws to pull prey back into the mouth in ratchet feeding. Filter feeding evades these problems by feeding on very small prey. The use of paradigms in functional analysis is discussed with special reference to this work. The paradigm method is shown to be the most suitable one. There has been repeated convergent and parallel evolution of adaptations to feed in wa

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1987.tb01727.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY