Primitive Mammals Research Articles

Central connections of the olfactory bulb in the American opossum (Didelphys virginiana): a light microscopic degeneration study.

Destructive lesions were made in the right olfactory bulb of 16 adult opossums. Following postoperative survival periods of 4 to 31 days, the animals were sacrificed and perfused with 10% Formalin. Frozen sections of the brain were cut in either the coronal, horizontal, or sagittal plane and processed by the Fink-Heimer II method. Degenerating axons of olfactory bulb neurons were traced caudally in the ipsilateral lateral olfactory tract (LOT). Small lesions revealed a topographic representation of the olfactory bulb within the LOT. The dorsal, lateral, and ventral parts of the bulb were, respectively, represented in the dorsal, intermediate, and ventral parts of the LOT. Terminal degeneration was observed in the superficial half of the molecular layer ipsilaterally in the following structures: anterior olfactory nucleus, anterior hippocampal rudiment, olfactory tubercle, piriform cortex, ventrolateral frontal neocortex, lateral entorhinal cortex, nucleus of the LOT, and the lateral aspect of the cortical amygdaloid nucleus. No degeneration was observed in the anterior limb of the anterior commissure. Dorsal and lateral parts of the olfactory bulb projected to the anterolateral aspect of the olfactory tubercle, whereas the ventral part projected heavily to the entire tubercle. There was no evidence of topographic projections to other olfactory structures. The observations of the present investigation indicated that the olfactory bulb projections in the opossum, a primitive mammal, are essentially comparable with those of placental mammals.

Comparative Physiology: Primitive Mammals. Ed. by K. Schmidt‐Nielsen, L. Bolis and C. R. Taylor. Pp. 338. (Cambridge University Press, 1980.) £20.00

Quarterly Journal of Experimental PhysiologyVolume 66, Issue 3 p. 343-344 ArticleFree Access Comparative Physiology: Primitive Mammals. Ed. by K. Schmidt-Nielsen, L. Bolis and C. R. Taylor. Pp. 338. (Cambridge University Press, 1980.) £20.00 B. P. Setchell, B. P. SetchellSearch for more papers by this author B. P. Setchell, B. P. SetchellSearch for more papers by this author First published: 16 July 1981 https://doi.org/10.1113/expphysiol.1981.sp002569AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume66, Issue3July 16, 1981Pages 343-344 RelatedInformation

Dairy Foods of the World – Evolution, Expansion, and Innovation

Millions of years ago before humans inhabited the earth, there were mammal-like creatures. These early mammals were smaller than hamsters and the quantities of milk produced were minute, barely sufficient to feed the young. Later in their evolutionary h/story, mammals increased in size and diversity through adaptations to a hostile environment. Being wild, however, primitive mammals neither collected nor stored their milk for later use. This impor tant adaptat ion was introduced by another mammal, the human.

The mammalian Harderian gland: morphology, biochemistry, function and phylogeny.

It is proposed that the Harderian glands are those ocular glands that have tubuloalveolar endpieces with wide lumina and secrete lipid by a merocrine mechanism.The Harderian gland occurs in various mammals, not only in eutherias but also in marsupials. However, as the gland has hereto-fore been studied almost exclusively in rodents and lagomorphs, it should be studied more in other groups of mammals, especially primitive mammals such as marsupials and insectivores.The secretory duct of the mammalian Harderian gland, as a rule, is single and opens near the third eyelid in the inner canthus. The whale Harderian gland is an exception as it is present as two masses and each of which has multiple excretory ducts. In rodents and lagomorphs, the orbital venous sinus is very well developed and surrounds almost all the orbital contents. Therefore, the surface of the gland is macroscopically smooth.Histologically, the gland has branched tubuloalveolar endpieces with wide lumina, and rarely has a duct system. It is quite difficult to detect a duct in usual histological sections. In rodents, the alveoli often contain two types of glandular cells, however, the significance of the difference between these two types is quite uncertain.The Harderian gland is the sole example in which glandular cells secrete lipid by a merocrine mechanism. The formation process of the secretory vacuoles within glandular cells is not known.In rodents and lagomorphs, the lipid of the gland is mainly either glyceryl ether diesters or wax esters, and similar to sebum. In rodents, the gland often contains porphyrin, but its significance is quite uncertain.The function of the Harderian gland probably varies among mammals. In aquatic mammals, the glandular secretion is thought to protect the eye from sea water. In rodents and lagomorphs, the gland may serve either as a sebaceous or a pheromonal gland.It appears most probable that phylogenetically the mammalian Harderian gland originated from the lacrimal gland of ancestral mammals from which all marsupials and eutherias have descended.

Picopsis pattersoni, n.gen. and sp., an unusual therian from the Upper Cretaceous of Alberta, and the classification of primitive tribosphenic mammals

A new therian mammal of primitive tribosphenic grade is described from the Upper Milk River Formation (Upper Cretaceous) of Alberta, Canada, and its relationships to other primitive tribosphenic therians are discussed. The new therian and its presumed nearest relatives form the basis of a new family within the Order Aegialodontia. A revised classification of the Infraclass Tribotheria is presented.

Brain mechanisms for offense, defense, and submission

AbstractA preliminary attempt is made to analyze the intraspecific aggressive behavior of mammals in terms of specific neural circuitry. The results of stimulation, lesion, and recording studies of aggressive behavior in cats and rats are reviewed and analyzed in terms of three hypothetical motivational systems: offense, defense, and submission. A critical distinction, derived from ethological theory, is made between motivating stimuli that simultaneously activate functional groupings of motor patterning mechanisms, and releasing and directing stimuli that are necessary for the activation of discrete motor patterning mechanisms. It is suggested that motivating stimuli activate pathways that converge upon sets of homogeneous neurons, called motivational mechanisms, whose activity determines the motivational state of the animal.A defense motivational mechanism is hypothesized to be located in the midbrain central gray. In addition to tactile, auditory, and visual inputs from the paleospinothalamic tract, lateral lemniscus, and (perhaps) from the pretectum, it may receive inputs from a major forebrain pathway whose functional significance is not yet understood.A submission motivational mechanism is also thought to be located in the central gray. In addition to inputs for defense, it is thought to receive a necessary input from a “consociate (social familiarity cue) modulator” located in the ventromedial hypothalamus, which can switch behavior from defense to submission. The location of the hypothetical offense motivational mechanism is not known, although the pathways by which it is activated are traced in some detail.Brain mechanisms of aggression in primitive mammals and in primates are apparently similar to those in rats and cats.

The primitive cynodontProcynosuchus: functional anatomy of the skull and relationships

An acetic acid prepared skull of the Upper Permian Karroo cynodontProcynosuchus delaharpeaeBroom is described and an attempt is made to interpret its anatomy in functional terms. The dentition is adapted for an insectivorous habit with an incipient form of tooth occlusion between specific upper and lower postcanines. A specialized form of tooth replacement ensures that the posterior postcanine teeth remain functional for as long a period as possible. The adductor jaw musculature shows a masseter-like muscle between the zygomatic arch and the lateral surface of the angular bone, in addition to the large temporalis muscle which has invaded the lateral face of the coronoid process. The possibility of a monotreme-like detrahens muscle rather than a reptilian depressor mandibuli being present for jaw opening is suggested. The quadrate is moveable. The anatomy of the internal nares indicates that an arrangement of Jacobson’s organ and associated nerves, blood vessels and glands comparable to that of monotremes was present. Interpretations of the various foramina of the snout are presented. Fleshy lips were probably present but the skin over the dorsal surface of the snout was tightly applied. The venous system of the head involves reduction of the vena capitis lateralis and the development of emissary veins comparable in general to those of mammals. The brain is comparable in size and relative development of its parts to that of living primitive mammals. There was incipient development of a monotreme-like membranous anterior lamina of the prootic. The stapes had a mechanical rôle associated with the moveable quadrate, in addition to its sound conducting role. It may have been capable of transmitting low frequency sound from the lower jaw as well as higher frequency sound from a tympanic membrane. The more advanced, Triassic cynodonts form a monophyletic group, of whichProcynosuchusis the sister-group. The archaic but highly specializedDviniais the sister-group of all other known cynodonts.

Decouverte dans le Paleocene du Maroc des plus anciens mammiferes eutheriens dáfique

A microvertebrate locality was discovered in the Southern part of the Ourzazate Basin (Morocco). The classical stratigraphic data as well as new elements given by Selacians allow us to date it form Lower Paleocene. Characid fishes, the oldest known to day, and an eutherian mammal fauna are associated with these Selacians. The mammal fauna includes Palaeoryctids, showing close affinities with the North American Upper Cretaceous genus Batodon, three forms which can be attributed to small carnivores, and still undetermined teeth. This fauna brings concrete elements to the problem of the african primitive mammal peopling and to the paleobiogeographical relationships of this continent.

Factors relating to energy conservation during sleep in mammals

It is proposed that sleep may serve a prime role as an energy conserver and immobilizer in the smaller and more primitive mammals, with REM sleep being particularly oriented to this purpose. However, with the evolution of the cortex and increasing body size, sleep may have become more directed towards the brain. While the earlier form of sleep may have been essentially REM sleep, this latter development of sleep may have been within non-REM sleep.

The Social Behaviour of Captive Muntjacs Muntiacus reevesi (Ogilby 1839)

The social behaviour of 8 captive muntjacs was studied from May to October 1970 and 1971. In 1970 close range observation and photography resulted in a descriptive account of the animal's social behaviour patterns. In 1971, 450 h of observation of undisturbed muntjacs living in a 2200 m2 enclosure were devoted to a quantitative study of social interactions. It was found that the social relationships of muntjacs are complex and subtale, maybe more than one might expect from a solitary and primitive mammal. Because of the animal's similarities with the ancestors of the Artiodactyls, a knowledge of the muntjac's social behaviour is essential for a proper understanding of the evolution and social behaviour of the order.

Essai d’interprétation de la répartition des Ascaridoidea chez les Mammifères

In an attempt to interpret the distribution of Ascaridoidea in Mammals and Birds, a scheme is proposed, based on the concept of geological periods of evolutionary expansion for parasitic lines. It is assumed that the evolutionary expansion period of Ascaridoidea in Mammals occurred after the diversification of primitive mammals; this would explain the absence of ascarids in these groups. Periods of evolution appear to coincide with the diversification of Carnivora and Sirenia, the first to become invaded; Artiodactyla and Equidae became invaded later, at the time of their diversification. The other cases of parasitism of Mammals by Ascarids are thought to be "captures".

Impact of cool temperatures on transformation of human and armadilio lymphocytes (Dasypus novemcinctus, Linn.) as related to leprosy.

A CENTURY-LONG search for an unaltered animal in which to study leprosy in humans culminated in the finding that the nine-banded armadillo (Dasypus novemcinctus, Linn.), a primitive mammal native to the southern Western Hemisphere, develops disseminated lepromatous leprosy following inoculation with Mycobacterium leprae isolated from human tissue1–3. Previous animals only developed leprosy following inoculation with leprosy bacilli after having been immunologically suppressed by neonatal thymectomy with or without irradiation of bone marrow4–8. Yet curiously the leprosy lesions occurred chiefly on the cooler tissues, the footpads.

Innervation of vibrissa follicles in the marsupial Trichosurus vulpecula

The innervation of the mystacial vibrissa follicles in the adult brush-tailed possum, T. vulpecula, has been studied by light and electron microscopy. One to five large nerve trunks penetrate the lower part of the follicle capsule and divide many times as they ascend and completely envelop the con- nective tissue sheath of the follicle. As many as 500 myelinated nerves have been observed in the mid region of the largest follicles. Above the mid region, most of the nerves move closer to the centre of the follicle and finally terminate within or near the outer layer of epithelial cells. Four main types of nerve endings have been observed: (1) Sensory receptor cells, called Merkel cells, with their associated neurites are numerous within the outer layer of epithelial cells. (2) Palisade endings, which are less common than the Merkel cell-neurite complexes, surround the upper part of the glassy membrane of the follicle. In transverse section each palisade ending appears as a flattened central neurite partially enveloped on either side by Schwann cell processes. (3) Bulbous endings occur in both the connective tissue sheath and in the outer layer of follicle epithelial cells. They are larger than types (1) and (2) and their ultrastructure varies markedly. (4) Compound endings occur within the connective tissue sheath of the follicle. They are uncommon but large and are composed of a chain of bulbous units joined by nerves; the entire ending may be encapsulated. Within each unit there is a tangle of nerve fibres. The Merkel cell-neurite complexes and the palisade endings in T. vulpecula are remarkably similar to those of eutherian mammals, suggesting that such sensory structures were features of primitive mammals.

Southern biogeography on the basis of continental drift: a review.

Several independent lines of evidence show that continental drift has occurred on a large scale. The southern super-continent Gondwanaland, rifted during the earlier Mesozoic, began to fragment during the Cretaceous. The larger Gondwanic continental areas experienced some aridity during the late Tertiary and Pleistocene, while other smaller land areas continued to enjoy moist isothermal conditions. Different climates have led to the selection of different elements from the same original Gondwanic flora, which largely accounts for the various floristic disjunctions of the southern hemisphere. There has also been some mingling with northern floras; much plant migration probably occurred during the Pleistocene. Many animal taxa show disjunct southern distributions, explicable in terms of continental drift. The early migrations of primitive mammals, in Cretaceous times, were followed by separate processes of evolution and extinction on the separate drifted continents of the Tertiary. Gondwanaland was an important centre of evolution. The mainly southern distribution of primitive angiosperms may indicate a Gondwanic origin for the group.

Prisms and tubules in multituberculate enamel.

Upper Cretaceous multituberculate tooth enamel was investigated by light microscopy, scanning electron microscopy and contact microradiography. The spatial arrangement of the crystallites in the enamel was well defined in prisms and interprismatic enamel. The diameter of the prisms and their mutual central distances were far greater than in the enamel of any known representative of present mammals. It is concluded that true prismatic enamel also existed in non-therian primitive mammals. Enamel tubules were present and were direct extensions of dentinal tubules. The enamel tubules crossed the course of the prisms and in cross-sections were found to be present in the interprismatic enamel as well as in prism cores. It is difficult to conceive that such tubules could be the product of ameloblasts, and it is concluded that they have a dentinal origin.

SOME FUNCTIONAL ASPECTS OF MOLAR EVOLUTION.

EvolutionVolume 26, Issue 3 p. 474-483 ArticleFree Access SOME FUNCTIONAL ASPECTS OF MOLAR EVOLUTION P. M. Butler, P. M. Butler Royal Holloway College, Englefield Green, Surrey, EnglandSearch for more papers by this author P. M. Butler, P. M. Butler Royal Holloway College, Englefield Green, Surrey, EnglandSearch for more papers by this author First published: September 1972 https://doi.org/10.1111/j.1558-5646.1972.tb01951.xCitations: 39AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume26, Issue3September 1972Pages 474-483 ReferencesRelatedInformation

Blood supply to primitive mammalian brains.

AbstractBrains of mammals are supplied by paired internal carotid arteries and also by paired vertebral arteries. The internal carotids distribute to the forebrain with its developing neopallium. The hindbrain with the expanding cerebellum and newly acquired middle cerebellar peduncle are supplied by the vertebral‐basilar system. In the opossum and armadillo the caudal rami of the internal carotid arteries resemble the patterns seen in submammals. The major source of blood to the posterior cerebral arteries is variable, coming from the basilar, the internal carotids or both. The ventral arterial circle (circulus arteriosus) is open as there is no anterior communicating artery in the two forms described. With the increase in size of the lateral lobes, the cerebellum of lower mammals is sufficiently larger and better developed to require a pair of inferior cerebellar arteries in addition to the phylogenetically older superior cerebellar arteries which originate from the basilar trunks. The latter are formed by the bifurcation of the basilar artery. The tectum in these forms is supplied by branches from the posterior cerebral and superior cerebellar arteries as well as tectal rami arising from the basilar trunks. Branches of the basilar artery going to the brainstem have a branching pattern similar to that seen in the submammals.The intrinsic patterns in both the opssum and armadillo are essentially like those observed in all vertebrates. They are remarkably constant and are easily recognized from one form to another. The arterioles penetrating the armadillo brain terminate in a continuous capillary plexus like the intrinsic plexuses observed in most of the submammals as well as in all mammals except marsupials. Arterioles penetrating the brain of the American opossum, as well as of all other marsupials, do not form a capillary plexus but terminate in capillary loops. Every penetrating arteriole is accompanied by a venule; each pair of vessels terminates in one or more capillary loops, thus constituting a true end‐system. However, as in the rest of its body, capillaries in the infundibular process and stalk, choroid plexuses, area postrema, supraoptic crest and subfornical organ are not paired but form freely anastomosing plexuses.The major developmental advance, i.e., the “mammalian shift,” in the blood supply to brains of primitive mammals is the addition of the vertebral arteries to supply the brainstem and an inferior cerebellar branch going to the cerebellum. The implications of these phylogenetic changes are discussed and related to the functional development.

A polygraphic and behavioral study of sleep in the pigeon ( Columba livia)

Studies of primitive mammals suggest that paradoxical sleep (PS) may have appeared late in mammalian evolution, well after the appearance of slow-wave sleep (SWS). Because birds and mammals are independently derived from ancient reptilian stock, the presence or absence of PS in birds is of considerable interest. A polygraphic and behavioral study of sleep patterns was conducted on eight young adult pigeons ( Columba livia). Paradoxical sleep was found to be present in the pigeon, occupying 6.9% of total sleep time. The EEG, EMG, EOG, respiration and brain temperature recordings indicated that pigeon PS is similar to mammalian PS. Arousal thresholds to neck shock stimuli were increased during PS as in mammals. The presence of PS in both classes may be due to inheritance from a common ancestor (e. g. homology), or to parallel evolution. Because it is absent in the most primitive mammal (echidna) we conclude that it has evolved independently in birds and therian mammals. Slow-wave sleep was also found to be similar to mammalian SWS. It was hypothesized on the basis of reptilian and mammalian studies that it, too, has evolved independently in birds and mammals.

The first Jurassic mammal from Scotland

R ecords of mammals in Mesozoic strata are rare: the earliest are of late Triassic age in Wales, S. Africa and China: two primitive mammal families (Eozo-strodontidae and Kuehneotheridae) are represented in these faunas. There then follows a long time gap until Late Jurassic, when mammals are known from the U.S.A., U.K., Portugal and Tanzania: these faunas include pantotheres, the stock from which almost all the later mammals arose. Between the Late Trias and Late Jurassic, the only known fauna is that of the Middle Jurassic of Stonesfield in Oxfordshire. Thus the discovery of a second site is of great importance: it occurs in the Estuarine Series of Skye in Scotland, and contains a fauna of tritylodonts and docodont mammals. The discovery of this fauna was made in August 1971 by Dr. M. Waldman and Mr. J. B. Dobinson during the course of a search for terrestrial vertebrates in the non-marine strata of Skye. Stratigraphy Since Hugh Miller (1858) described the occurrence of Jurassic vertebrate fossils on the Isle of Eigg, further vertebrates of similar age have been found in the Hebridean region. The richest material so far recovered has been from the Bathonian (Middle Jurassic) of Eigg ( Hudson 1966 ), and the most recent find is that of plesiosaur remains from the Bearreraig Sandstone (Bajocian) near Rigg, Isle of Skye ( Hudson & Morton 1969 ). All the Jurassic vertebrate remains known from this area are those of fish and reptiles and occur in a variety of localities. ( Miller 1858 , Peach 1910 , Arkell

Evolution of the Pulvinar (Part 2 of 2)

Our evidence from both cytoarchitecture and studies of connections suggests that LE GROS CLARK was correct in postulating that the lateral posterior nucleus of primitive mammals is the homologue to the primate pulvinar. It seems evident that during mammalian evolution both this region of the thalamus and its cortical target have grown larger and more complex. Truly intrinsic subdivisions may have appeared not only in the primates but also independently in other mammalian lines of descent, such as the carnivores. One main goal of our laboratory is to ask how functional subdivisions are related to the increasing subdivisions of structure. Our hope is that this line of inquiry might contribute to an understanding of those functions most recently evolved in mammalian evolution.