A new durophagous phocid (Mammalia: Carnivora) from the late Neogene of Peru and considerations on monachine seals phylogeny

Re-evaluation of Morphological Characters Questions Current Views of Pinniped Origins.Koretsky, I. A., Barnes, L. G., Rahmat, S. J. -Th e origin of pinnipeds has been a contentious issue, with opposite sides debating monophyly or diphyly. Th is review uses evidence from the fossil record, combined with comparative morphology, molecular and cytogenetic investigations to evaluate the evolutionary history and phylogenetic relationships of living and fossil otarioid and phocoid pinnipeds. Molecular investigations support a monophyletic origin of pinnipeds, but disregard vital morphological data. Likewise, morphological studies support diphyly, but overlook molecular analyses. Th is review will demonstrate that a monophyletic origin of pinnipeds should not be completely accepted, as is the current ideology, and a diphyletic origin remains viable due to morphological and paleobiological analyses. Critical examination of certain characters, used by supporters of pinniped monophyly, reveals diff erent polarities, variability, or simply convergence. Th e paleontological record and our morphological analysis of important characters supports a diphyletic origin of pinnipeds, with otarioids likely arising in the North Pacifi c from large, bear-like animals and phocids arising in the North Atlantic from smaller, otter-like ancestors. Although members of both groups are known by Late Oligocene time, each developed and invaded the aquatic environment separately from their much earlier, common arctoid ancestor. Th erefore, we treat the superfamily Otarioidea as being monophyletic, including the families Enaliarctidae, Otariidae (fur seals/sea lions), Desmatophocidae, and Odobenidae (walruses and extinct relatives), and the superfamily Phocoidea as monophyletic, including only the family Phocidae, with four subfamilies (Devinophocinae, Phocinae, Monachinae, and Cystophorinae).

Section: Alisphenoid Canalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Re-Evaluation of Morphological Characters Questions Current Views of Pinniped Origins

Koretsky¹,

Barnes²,

Rahmat³

2016

“…Recently, Amson and Muizon (2014) described the mandibular/dental morphology and mastication musculature of the monachine seal Hadrokirus martini (Late Miocene to Early Pliocene). Th eir conclusion that a large, wide coronoid process suggests the presence of a powerful temporalis muscle is further supported by this present study.…”

Section: Hyenasmentioning

confidence: 99%

“…Additionally, a large-sized mandibular ramus indicates a large insertion area for a powerful masseter muscle and a well-developed angular process indicates strong pterygoid musculature, similar to our fi ndings in hyenas. Th e dentition of Hadrokirus martini reveals massive premolars similar to Crocuta and considerably greater pressure during bite force (Amson, Muizon, 2014).…”

Section: Hyenasmentioning

confidence: 99%

Diversity Of Mandibular Morphology In Some Carnivorans

Rahmat¹,

Koretsky²

2015

Diversity of Mandibular Morphology in Some Carnivorans. Rahmat, S. J. Koretsky, I. A. -Comparison of mandibular morphology of some aquatic (seals, walruses, and sea otters) and terrestrial (hyenas and pandas) carnivorans demonstrates a rather general pattern correlating size of condyloid angle, size of gape, and diet. Structural diff erences of carnivoran jaws reveal morphological and ecological adaptations that are directly correlated with availability of prey, diving depth, feeding competition and specialized feeding methods. Specifi cally, the inclination of the condyloid process relative to the axis of the alveolar row (= condyloid angle) can be used to determine dietary preferences, including size of prey. Generally, carnivorans with a large condyloid angle feed on larger prey, while a low condyloid angle suggests feeding on small prey or can be an advantageous feeding mechanism. Mirounga angustirostris (Northern elephant seal) displays sex-specifi c characters in cranial and postcranial elements. Likewise, signifi cant sexually dimorphic diff erences in the size of condyloid angle imply that deeper-diving male Northern elephant seals have a feeding niche dissimilar to that of females. Morphological assessment of male M. angustirostris suggests they are bottom-feeding seals that utilize a suction-feeding mechanism to capture small prey and crush shells with their teeth, which become weaker as they age.K e y w o r d s: marine mammal, seal, mandibular morphology, carnivoran, gape, condyloid angle.Разнообразие в морфологии челюстей некоторых хищных животных. Рахмат С. Й., Корецкая И. А. -Сравнение морфологии нижней челюсти некоторых водных (тюлени, моржи и морские выдры) и наземных хищников (гиены и панды) демонстрирует довольно общую картину корреляции между величиной мыщелкового угла, расстоянием между открытыми челюстями и характером питания. Структурные различия челюстей хищников выявляют морфологические и экологические адаптации, прямо связаны с доступностью добычи, глубиной погружения, конкуренцией за ресурсы и специализированными методами кормления. В частности, угол наклона мыщелкового отростка по отношению к оси альвеолярного ряда (= мыщелковый угол) может быть использован для определения трофических предпочтений, в том числе размера добычи. Как правило, хищники с большим мыщелковым углом челюсти охотятся на крупную добычу, в то время как небольшой мыщелковый угол предполагает питание мелкой добычей или может быть эффективным трофическим механизмом. Mirounga angustirostris (северный морской слон) демонстрирует признаки полового диморфизма черепных и посткраниальных элементов. Кроме того, значительные половые различия в размерах мыщелкового угла означают, что экология питания самцов северных морских слонов, способных к глубоководному погружению, существенно отличается от таковой у самок. Морфологическая оценка самцов М. angustirostris позволяет предположить, что они являются тюленями, которые кормятся на глубине и используют механизм кормления всасыванием, захватывая мелкую добычу и разрушая раковины зу...

“…Th eir examination of the associated postcranial bones with fragments of the skull and mandible strongly supported Koretsky's (2001) ecomorphotype theory. In addition, our current method of associating isolated bones followed those of Muizon (1981), Koretsky and Grigorescu (2002), Koretsky and Ray (2006) and Amson and Muizon (2014), who described more complete associated partial skeletons.…”

mentioning

confidence: 99%

First Record of Postcranial Bones in Devinophoca emryi (Carnivora, Phocidae, Devinophocinae)

Rahmat¹,

Koretsky²

2016

First Record of Postcranial Bones in Devinophoca emryi (Carnivora, Phocidae, Devinophocinae). Rahmat, S. J., Koretsky, I. -Th e Devinophoca emryi material from the early Badenian, early Middle Miocene (16.26-14.89 Ma) presents mixed cranial and especially postcranial characters with the three extant phocid subfamilies (Cystophorinae, Monachinae and Phocinae), as well as unique postcranial characters not seen in any taxa. Th ese distinguishing characters (i. e. well-outlined, large oval facet on greater tubercle of humerus; broader width between the head and lesser tubercle of humerus; femoral proximal epiphysis larger than distal; thin innominate ilium that is excavated on ventral surface) demonstrate that this material belongs to a recently described species (D. emryi). During ecomorphotype analyses, fossil humerus and femur bones were directly associated with their corresponding mandible to reveal associations based on Recent morphological analogues. Strong correlation between ecomorphotypes and postcranial morphology supports placement of this material to D. emryi and not its sister taxon, D. claytoni. Th e previously described skull, mandible and teeth and postcranial bones described herein were discovered at the same locality during excavations at the base of the Malé Karpaty Mountains (Slovakia), at the junction of the Morava and Danube rivers. Th e geological age of D. emryi and the presence of mixed characters strongly suggest that this species was an early relative to the ancestor of seals, possibly being a terminal branch of the phocid tree. Th is material allows for emended diagnoses of the species, updated assessments of geographical distribution and provides further material for clarifi cation of controversial phylogenetic relationships in Phocidae.