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Patterns of the internal carotid and cerebral carotid arteries, ventral view, A-Turkey, B-Goose. 1-Right internal carotid artery, 2-left internal carotid artery, 3-right cerebral carotid artery, 4-left cerebral carotid artery, 5-optic chiasma, 6-intercarotid anastomosis, 7-cranial ramus, 8-caudal ramus, 9-basilar artery.
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The right and left internal carotid arteries of the obtained birds were injec-ted with coloured-latex to picture and examine their patterns through the brain. They were present and equally prominent in all the cadavers exami-ned. An anastomosis, hence, was observed between extracranially and intra-cranially coursing arteries. The intercarotid anast...
Citations
... Paired carotid arteries run through the neck, extending laterally and dividing into two branches, the internal and external carotids, supplying arterial blood to the brain (Baumel 1993). The internal carotids run rostromedially through two bony carotid canals and transversely to the long axis of the skull, before contacting dorsally the distal portion of the hypophysis (Aslan et al. 2006;Porter and Witmer 2016). In most birds at this level, an intercarotid anastomosis is established through a transverse vessel that connects the right and left arteries. ...
Brain morphology has become a key element to predict a wide array of cognitive and behavioral, sensory and motor abilities, and to determine evolutionary rates of phenotypic transformation. Our information on early bird brain morphology comes of natural endocasts or studies of the intracranial cavity. Although the first studies of fossil bird brains were published almost two centuries ago, there is still relatively little known about the avian brain and its evolution compared with other groups such as mammals. This is due primarily to the fact that few three-dimensionally preserved skulls of early birds are recognized. The avian brain occupies the entire intracranial cavity, so that it is possible to reconstruct high-quality 3D virtual endocast models that can be used as excellent proxies for both volume and morphology of the brain. This technique has driven advances in avian paleoneurology from 2000 onwards. In this chapter, we provide a holistic view of the main features of the avian brain and senses, its disparity and potential use in paleobiological inferences, and discuss the main changes across the transition from non-avian theropods to derived Neornithes.
... In the neotropical Piciformes studied here, the left and right cerebral carotids may be connected by a highly visible transverse vessel that forms an H-shaped intercarotid anastomosis or a side-to-side connection, resembling an X (Aslan et al., 2006;Baumel & Gerchman, 1968). Ramphastidae and Picidae have the first type while Galbulidae and Bucconidae have the second one. ...
We used three‐dimensional digital models to investigate the brain and endosseous labyrinth morphology of selected Neotropical Piciformes (Picidae, Ramphastidae, Galbulidae and Bucconidae). Remarkably, the brain morphology of Galbulidae clearly separates from species of other families. The eminentiae sagittales of Galbulidae and Bucconidae (insectivorous with high aerial maneuverability abilities) are smaller than those of the toucans (scansorial frugivores). Galbula showed the proportionally largest cerebellum, and Ramphastidae showed the least foliated one. Optic lobes ratio relative to the telencephalic hemispheres showed a strong phylogenetic signal. Three hypotheses were tested: (a) insectivorous taxa that need precise and fast movements to catch their prey, have well developed eminentiae sagittales compared to fruit eaters, (b) species that require high beak control would show larger cerebellum compared to other brain regions and higher number of visible folia and (c) there are marked differences between the brain shape of the four families studied here that bring valuable information of this interesting bird group. Hypotheses H1 and H2 are rejected, meanwhile H3 is accepted. We use 3D digital models of the brain cavity and inner ear of species of Picidae, Ramphastidae, Galbulidae and Bucconidae to better understand functional and ecological implications. We found marked differences among the brains of the four families, being G. ruficauda the most different one. Fruit eaters (Ramphastidae) had the biggest eminenta sagittales ratio. The cerebellum showed variable sizes and variable visible foliation among species. Only the optic lobe ratio has a phylogenetic signal.
... Research into avian cephalic vasculature has at times been very active. The literature spans at least 150 years, from general studies by Neugebauer (1845;turkeys), Baumel (1975Baumel ( , 1993; domestic fowl), Sedlmayr (2002; ducks and other Galloanseres), and Holliday et al. (2006;flamingos) to more focused studies on, for example, avian encephalic arterial patterns (Aslan et al., 2006;Verduzco et al., 2009;Nazer and Campos, 2011).This research includes both vascular anatomy and its role in thermal biology, which is critical to the understanding of avian physiological thermoregulation. In 1970, Richards (1970) reported a temperature differential between the brain and body in chickens, with the hypothalamic region of the brain being roughly 18 C cooler than colonic temperatures. ...
... The vascular anatomy of Galliformes is well known in the literature (Neugebauer, 1845;Baumel, 1975Baumel, , 1993Crowe and Crowe, 1979;Richards, 1967Richards, , 1968Richards, , 1970Sedlmayr, 2002;Aslan et al., 2006) and serves as a wellknown model with which to compare more derived taxa. Turkeys are large-bodied birds with unfeathered heads, hold a broad range with varying temperatures and environmental conditions, and display vascular features useful for thermoregulation (Buchholz, 1996). ...
The general anatomy of avian cephalic blood vessels is well known and there are published details of their role in physiological thermoregulation. Unfortunately, the finer details of vascular pathways to and from sites of thermal exchange are not well known. Additionally, the role of the rete ophthalmicum (RO), a vascular heat exchanger in the temporal region, has been investigated in terms of brain temperature regulation, yet only the arteries have received substantial attention. Without anatomical details of both the arterial and venous pathways, the role of blood vessels in physiological thermoregulation is incomplete. Cephalic vascular anatomy of multiple avian taxa was investigated using a differential-contrast, dual-vascular injection technique and high-resolution X-ray microcomputed tomography. Sites of thermal exchange (oral, nasal, and orbital regions) and the RO were given special attention due to their known roles in cephalic thermoregulation. Blood vessels to and from sites of thermal exchange were investigated to detect conserved vascular patterns and their ability to deliver cooled blood to the RO and dural venous sinus. Sites of thermal exchange were supplied by arteries directly and through collateral pathways. Veins were found to offer multiple pathways that could influence the temperature of neurosensory tissues, as well as pathways that would bypass neurosensory tissues. These results question the paradigm that arterial blood from the RO is the primary method of brain cooling in birds. A shift in the primary role of the RO from brain cooling to regulating and maintaining the temperature of the avian eye should be further investigated. This article is protected by copyright. All rights reserved.
... Ksepka et al. (2012) found variation in penguins, with the fossil stem penguin Paraptenodytes antarcticus and the king penguin, Aptenodytes patagonicus, exhibiting H-type anastomoses, whereas the others exhibit an X-type. Other studies have noted similar variation amongst galloanseriformes (Aslan et al., 2006) and in birds in general (Baumel & Gerchman, 1968). ...
The dodo (Raphus cucullatus) became extinct only 100 years after humans first arrived on the Indian Ocean island of Mauritius. Even though it has become an example of oddity, obsolescence, stupidity, and extinction, most aspects of its biology are still unknown. We used high-resolution X-ray computed tomography (CT) scanning to examine the endocranial morphology of the dodo and compare this virtual endocast to eight close relatives. Enlarged olfactory bulbs are a shared characteristic of the Raphinae and posteriorly angled semicircular canals are particular to the dodo compared with the other eight species sampled here. A regression of log endocranial volume against log body size shows that the dodo has an endocranial volume on par with other pigeons. Aspects of the dodo's biology are discussed in relation to these endocranial features.
... In Antarctic Fossil 1, the external opening of the ostium canalis carotici (exiting the braincase) is located caudomedial to the lower edge of the meatus acusticus externus and the internally opening canal is caudolateral to the sella. In birds, the left and right internal carotid arteries (derived from the common carotid artery; Aslan et al., 2006) approach one another immediately caudal to the optic chiasm to communicate through the anastomosis intercarotidea, which lies in the fossa hypophysealis at the base of the skull, directly caudal to the hypophysis. A low angle of convergence (apex located at the entrance of the carotid in the hypophysis) is exhibited by Antarctic Fossil 1 (62 ) compared with Paraptenodytes (94 ) and extant penguins (113 -123 ) ( Table 2). ...
Penguins have a more than 60 million year long evolutionary history. Thus, stem lineage fossil taxa are key to understanding their evolution. Here, we present data on three virtual endocasts from stem penguin skulls collected from the Eocene La Meseta Formation of Seymour Island (Antarctica), along with comparative data from extant penguins and outgroups. These fossils appear to belong to three distinct species, and represent both the oldest (34.2 Ma) and the most basal penguin taxa that have yielded endocast data. Data collected from the fossils provide new support for several important shifts in neuroanatomy and cranial skeletal anatomy along the transition from stem to crown penguins, including (1) caudal expansion of the eminentia sagittalis, (2) an increase in the overlap of the telencephalon onto the cerebellum, (3) reduction of the bulbus olfactorius, and (4) loss of the interaural pathway. The large semicircular canal diameters of the Antarctic fossils as well as the more crownward stem penguin Paraptenodytes antarcticus together suggest that canal size increased in basal penguins relative to outgroup taxa but later decreased near the crown radiation. As in most other wing-propelled diving birds, the endocasts lack evidence of cerebellar folds and possess a relatively large floccular recess. Several aspects of the endocast morphology, including the exposure of the tectum opticum in dorsal view and the rostral displacement of the eminentia sagittalis away from the border of the cerebellum, are seen neither in crown penguins nor in Procellariiformes (the extant sister clade to Sphenisciformes) and so appear to represent unique characters of these stem taxa.
... It has been suggested that pituitary volume is not phylogenetically variable but rather scales with body size [37]. The failure of the internal carotid arteries to anastomose, unlike the condition in Aves [38,39], is a plesiomorphic condition also found in Incisivosaurus [34], Zanabazar [35], and Archaeopteryx (personal observation of Digimorph.org/specimens/ Archaeopteryx_lithographica) (Fig. 5). ...
The high degree of encephalization characterizing modern birds is the product of a long evolutionary history, our understanding of which is still largely in its infancy. Here we provide a redescription of the endocranial space of the oviraptorosaurian dinosaur Conchoraptor gracilis with the goal of assessing the hypothesis that it shares uniquely derived endocranial characters with crown-group avians. The existence of such features has implications for the transformational history of avian neuroanatomy and suggests that the oviraptorosaur radiation is a product of the immediate stem lineage of birds-after the divergence of Archaeopteryx lithographica. Results derived from an expanded comparative sample indicate that the strong endocranial similarity between Conchoraptor and modern birds largely reflects shared conservation of plesiomorphic features. The few characters that are maintained as being uniquely expressed in these two taxa are more likely products of convergence than homology but still indicate that the oviraptorosaur endocranial cavity has much to teach us about the complex history of avian brain evolution.
... 16 Birds have a well developed arterial communication between ICAs (cerebral intercarotid anastomosis; 'H', 'X' or 'I' type). 14,15 The commonness of CW and analog structures indicates that its function is not compensatory in the case of occlusion event, since the majority of birds and other animals do not die from cerebrovascular events. It is more likely that CW is a convergent evolutionary structure that has a function in physiological conditions. ...
Nearly 400 years ago, Thomas Willis described the arterial ring at the base of the brain (the circle of Willis, CW) and recognized it as a compensatory system in the case of arterial occlusion. This theory is still accepted. We present several arguments that via negativa should discard the compensatory theory. (1) Current theory is anthropocentric; it ignores other species and their analog structures. (2) Arterial pathologies are diseases of old age, appearing after gene propagation. (3) According to the current theory, evolution has foresight. (4) Its commonness among animals indicates that it is probably a convergent evolutionary structure. (5) It was observed that communicating arteries are too small for effective blood flow, and (6) missing or hypoplastic in the majority of the population. We infer that CW, under physiologic conditions, serves as a passive pressure dissipating system; without considerable blood flow, pressure is transferred from the high to low pressure end, the latter being another arterial component of CW. Pressure gradient exists because pulse wave and blood flow arrive into the skull through different cerebral arteries asynchronously, due to arterial tree asymmetry. Therefore, CW and its communicating arteries protect cerebral artery and blood-brain barrier from hemodynamic stress.Journal of Cerebral Blood Flow & Metabolism advance online publication, 29 January 2014; doi:10.1038/jcbfm.2014.7.
... La descripción de esta estructura es importante ya que interviene de manera importante en la distribución del flujo sanguíneo a nivel cerebral. Recientes hallazgos fueron descritos por (Aslan et al. 2006) quien detalla la vasculatura arterial en aves domésticas y de ornato, entre estas se encuentra una ave originaria de Turquía, el Denizli rooster (G. gallus domestica), gallo doméstico, faisán, faisán plateado, ganso y pavo. ...
... Aunque en la literatura se menciona que la vasculatura aviar es semejante a la de los mamíferos (Jessen C 2001, Baumel & Gerchman 1968, existen diferencias estructurales de importancia que deben describirse y considerarse, sobre todo para aquellos investigadores que pudieran considerar a las aves como modelos experimentales en estudios de hipoxia-isquemia, aprendizaje, así como en analogías vasculares entre aves y mamíferos, anastomosis intercarotídea y polígono de Willis respectivamente. Existen en la literatura diversas fuentes de consulta, libros (Ghetie et al. 1981, McLelland 1992, Sisson & Grossman 1983) y publicaciones científicas (Pettit et al.1981, Aslan et al. 2006, las cuales no son lo suficientemente representativas de la vasculatura cerebral en el gallo doméstico. ...
... Otra diferencia importante entre aves y mamíferos es la relacionada con la formación de la Arteria Basilar (AB), la cual se deriva de la Arteria o Rama Caudal Derecha (ACD), Aslan et al. 2006), describe que la arteria basilar puede estar formada por la Arteria o Rama caudal Izquierda en el faisán, y el pavo, mientras que en el gallo doméstico y el ganso deriva de la Rama Derecha, lo que coincide con nuestros hallazgos. Es importante mencionar la ausencia de las arterias vertebrales en el gallo doméstico. ...
Se describe la vasculatura arterial carotídea-cerebral del gallo doméstico (Gallus gallus Linnaeus). Se utilizaron 10 gallos de 2.5 kg de peso, estirpe Rhode Island, los cuales fueron sometidos a la técnica de conservación replesión vascular. Se concluyó que la anastomosis intercarotídea, la formación de la arteria basilar y la ausencia de las arterias vertebrales son los componentes más sobresalientes de la vasculatura cefálica. Se propone estandarizar la nomenclatura de las diversas estructuras anatómicas y vasculares ligadas a la vasculatura arterial carotídea-cerebral ya que son confusas en las diversas publicaciones.
Intracranial arterial vascular anatomy is well known in humans, but it is lacking for most mammalian and non-mammalian model species, especially concerning the origin of the basilar artery (BA).
We have studied the encephalic arteries in three different species of birds and eight different species of mammals using formalin-fixed brains injected with arterial red latex. Our results and literature analysis indicate that, for all vertebrates, the internal carotid artery (ICA) supplies the brain and divides into two branches: a cranial branch and a caudal branch.
The difference between vertebrates lies in the caudal branch of the ICA. For non-mammalian vertebrates, the caudal branch is the origin of the BA, and the vertebral artery (VA) is not involved in brain supply. For mammals, the VA supplies encephalic arteries, but in two different ways. In fact, there are two types of encephalic artery organization.
In the first type of organization, mostly found in ungulates, the carotid rete mirabile supplies the encephalic arteries, the caudal branch is the origin of the BA, and the VA is indirectly involved in carotid rete mirabile blood supply. We believe that the carotid rete mirabile may be the result of occipitocervical biomechanics and climatic adaptations.
The second type of encephalic artery organization for mammals is the same as in humans. The caudal branch of the ICA serves as the posterior communicating artery, and the BA originates from both VAs.
We describe the carotid-cerebral arterial vasculature of the domestic rooster (Gallus gallus Linnaeus). Ten cocks race Rhode Island of 2.5 kg of weight were used, which were subjected to vascular replesion conservation technique. It was concluded that anastomosis intercarotidea, the formation of the basilar artery and the absence of the vertebral arteries are the most significant components of the cephalic vasculature. It is proposed to standardize the nomenclature of the arteries of the brain-stem carotid arterial because of the confusing terminology used by various authors.
