87-688: Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia . It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles . Ankylosaurs were bulky quadrupeds , with short, powerful limbs. They are known to have first appeared in North Africa during the Middle Jurassic , and persisted until the end of the Late Cretaceous . The two main families of ankylosaurians, Nodosauridae and Ankylosauridae are primarily known from
174-515: A "strongly curved" back (an error based on the alleged similarity to stegosaurs and glyptodonts , as ankylosaurs have flat backs). Therefore, "rigid lizard" and "curved lizard" could be additional meanings applied to the name of ankylosaurs. Ankylosauria and Stegosauria together form the two major subgroups of Thyreophora , a group of armoured dinosaurs distinct from ornithopods and marginocephalians . Historically used for forms lacking large vertical plates, Kenneth Carpenter proposed in 1997
261-523: A decrease in abundance of leaf-chewing larvae in the fall when hardwood leaf palatability decreases due to increased tannin levels which results in a decline of arthropod species richness , and increased palatability of plant communities at higher elevations where grasshoppers abundances are lower. Climatic stressors such as ocean acidification can lead to responses in plant-herbivore interactions in relation to palatability as well. The myriad defenses displayed by plants means that their herbivores need
348-623: A greater and more diverse set of resources. Coevolution and phylogenetic correlation between herbivores and plants are important aspects of the influence of herbivore and plant interactions on communities and ecosystem functioning, especially in regard to herbivorous insects. This is apparent in the adaptations plants develop to tolerate and/or defend from insect herbivory and the responses of herbivores to overcome these adaptations. The evolution of antagonistic and mutualistic plant-herbivore interactions are not mutually exclusive and may co-occur. Plant phylogeny has been found to facilitate
435-465: A herbivore in a dense forest would spend more time handling (eating) the vegetation because there was so much vegetation around than a herbivore in a sparse forest, who could easily browse through the forest vegetation. According to the Holling's disk equation, a herbivore in the sparse forest would be more efficient at eating than the herbivore in the dense forest. The marginal value theorem describes
522-489: A length of four to five centimeters. Some other ankylosaurians are known to have such osteoderms to protect the flanks. These eight scutes were not in apparent association with any skeletal element except one that was directly adjacent to a neural arch of a vertebra. The small number of such scutes may indicate that the rump was not very heavily armored. Near the left hand was a cluster of four smaller osteoderms, fifteen to twenty millimeters in diameter, with more pointed keels. On
609-495: A mutual relationship with the plant species that they forage by digging and disturbing the sediment which removes competing plants and subsequently allows colonization of other plant species. When herbivores are affected by trophic cascades , plant communities can be indirectly affected. Often these effects are felt when predator populations decline and herbivore populations are no longer limited, which leads to intense herbivore foraging which can suppress plant communities. With
696-557: A new patch of food when the patch they are currently feeding on requires more energy to obtain food than an average patch. Within this theory, two subsequent parameters emerge, the Giving Up Density (GUD) and the Giving Up Time (GUT). The Giving Up Density (GUD) quantifies the amount of food that remains in a patch when a forager moves to a new patch. The Giving Up Time (GUT) is used when an animal continuously assesses
783-715: A result of their plant-based diet, herbivorous animals typically have mouth structures ( jaws or mouthparts ) well adapted to mechanically break down plant materials, and their digestive systems have special enzymes (e.g. amylase and cellulase ) to digest polysaccharides . Grazing herbivores such as horses and cattles have wide flat- crowned teeth that are better adapted for grinding grass , tree bark and other tougher lignin -containing materials, and many of them evolved rumination or cecotropic behaviors to better extract nutrients from plants. A large percentage of herbivores also have mutualistic gut flora made up of bacteria and protozoans that help to degrade
870-1043: A same-definition junior synonym of Ankylosauria. The clade Euankylosauria was named by Soto-Acuña and colleagues in 2021 in their description of a unique basal ankylosaur Stegouros to represent the grouping uniting ankylosaurids and nodosaurids, to the exclusion of their newly discovered clade Parankylosauria . This clade is formally defined in the PhyloCode as "the largest clade containing Ankylosaurus magniventris and Nodosaurus textilis , but not Stegouros elengassen ". Scelidosaurus Stegosauria Kunbarrasaurus Antarctopelta Stegouros Cedarpelta Dongyangopelta Gargoyleosaurus Gastonia Hylaeosaurus Mymoorapelta Panoplosaurus Peloroplites Polacanthus Hoplitosaurus Sauroplites Taohelong Nodosaurinae Aletopelta Chuanqilong Liaoningosaurus Gobisaurus Shamosaurus Ankylosaurinae A 2023 review of Thyreophora rejects
957-438: A secondary palate. The row of teeth starts slightly in front of the lacrimal bone and continues below the eye socket. The entire top of the eye socket is formed by fused supraoccipitalia that form a continuous thickened canopy. Similar to Kunbarrasaurus the posterior parts of the skull are not fused so that the sutures remain visible. These parts are rough with pits so that raised bone pates or horn plates were probably present. In
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#17327901695491044-635: A single plant can have hundreds of different chemical defenses. Chemical defenses can be divided into two main groups, carbon-based defenses and nitrogen-based defenses. Plants have also changed features that enhance the probability of attracting natural enemies to herbivores. Some emit semiochemicals, odors that attract natural enemies, while others provide food and housing to maintain the natural enemies' presence, e.g. ants that reduce herbivory. A given plant species often has many types of defensive mechanisms, mechanical or chemical, constitutive or induced, which allow it to escape from herbivores. According to
1131-422: A small bump at the upper end, in the same position in which Stegosauria have a tubercule for the attachment of the musculus triceps brachii . The radius is slender but the ulna is robust and broadened at the top with a well-developed olecranon , an upper projection to bend the elbow. An ulnare was presumably present in the wrist; this is indicated by the discovery in the left wrist of a small U-shaped element that
1218-574: A terrestrial mammal to be called a grazer, at least 90% of the forage has to be grass, and for a browser at least 90% tree leaves and twigs. An intermediate feeding strategy is called "mixed-feeding". In their daily need to take up energy from forage, herbivores of different body mass may be selective in choosing their food. "Selective" means that herbivores may choose their forage source depending on, e.g., season or food availability, but also that they may choose high quality (and consequently highly nutritious) forage before lower quality. The latter especially
1305-443: A thick stratum corneum. On the undersides there are perpendicular intersecting notches for the attachment of fibers that presumably connect the plates to the skin. Those notches are typical for Parankylosauria. Thus, a flexible armor was formed. Thirteen "free" vertebrae have been preserved in the tail base. Five additional vertebrae are enclosed in a structure made of osteoderms that has been compared to an Aztec macuahuitl . After
1392-399: A tradeoff however, between foraging on many plant species to avoid toxins or specializing on one type of plant that can be detoxified. Herbivore modification is when various adaptations to body or digestive systems of the herbivore allow them to overcome plant defenses. This might include detoxifying secondary metabolites , sequestering toxins unaltered, or avoiding toxins, such as through
1479-438: A trophic cascade involved plant-herbivore interactions are coral reef ecosystems. Herbivorous fish and marine animals are important algae and seaweed grazers, and in the absence of plant-eating fish, corals are outcompeted and seaweeds deprive corals of sunlight. Agricultural crop damage by the same species totals approximately $ 100 million every year. Insect crop damages also contribute largely to annual crop losses in
1566-467: A typical ankylosaur feature, but they have hollow sides like Stegosauria. Towards the rear of the vertebral column, the transverse processes rise steeper, up to 60° on the posterior back. The vertebrae have high neural arches with both the pedicles and the neural spines reaching a considerable length. The anterior joint processes are U-shaped in top view. The sacrum has four true sacral vertebrae and an anterior sacral rod of two captured dorsosacrals that touch
1653-579: A variety of physical and metabolic alterations in the way the host plant interacts with itself and other surrounding biotic factors. Fungi, bacteria, and protists that feed on living plants are usually termed plant pathogens (plant diseases), while fungi and microbes that feed on dead plants are described as saprotrophs . Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants . There is, however, no single exclusive and definitive ecological classification of consumption patterns; each textbook has its own variations on
1740-527: A variety of skills to overcome these defenses and obtain food. These allow herbivores to increase their feeding and use of a host plant. Herbivores have three primary strategies for dealing with plant defenses: choice, herbivore modification, and plant modification. Feeding choice involves which plants a herbivore chooses to consume. It has been suggested that many herbivores feed on a variety of plants to balance their nutrient uptake and to avoid consuming too much of any one type of defensive chemical. This involves
1827-460: Is a model for predicting animal behavior while looking for food or other resources, such as shelter or water. This model assesses both individual movement, such as animal behavior while looking for food, and distribution within a habitat, such as dynamics at the population and community level. For example, the model would be used to look at the browsing behavior of a deer while looking for food, as well as that deer's specific location and movement within
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#17327901695491914-403: Is aided in reproduction. Plants can also be indirectly affected by herbivores through nutrient recycling , with plants benefiting from herbivores when nutrients are recycled very efficiently. Another form of plant-herbivore mutualism is physical changes to the environment and/or plant community structure by herbivores which serve as ecosystem engineers , such as wallowing by bison. Swans form
2001-439: Is an animal anatomically and physiologically evolved to feed on plants , especially upon vascular tissues such as foliage , fruits or seeds , as the main component of its diet . These more broadly also encompass animals that eat non-vascular autotrophs such as mosses , algae and lichens , but do not include those feeding on decomposed plant matters (i.e. detritivores ) or macrofungi (i.e. fungivores ). As
2088-480: Is connected to the proximal surface of the fifth metacarpal bone. The hand claws are hoof-shaped, not pointed. The second finger is reduced to two phalanges as in the Stegosauria. The second finger ends in a flat disc-shaped phalanx that is blunt and probably no longer had a claw at all. More such phalanges have been found around both hands, suggesting the same was true for the third, fourth and fifth fingers. In
2175-412: Is correspondingly flattened. At the fifteenth to eighteenth vertebrae, which are in the weapon, a CAT scan shows that the anterior joint processes, the prezygapophyses, are short while the posterior joint processes extend over the posterior vertebra, fused together on their inner sides to form a wedge-shaped structure in top view, filling a corresponding V-shaped space between the anterior joint processes of
2262-431: Is derived from Latin herba 'small plant, herb' and vora , from vorare 'to eat, devour'. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants , algae and photosynthesizing bacteria . More generally, organisms that feed on autotrophs in general are known as primary consumers . Herbivory is usually limited to animals that eat plants. Insect herbivory can cause
2349-563: Is determined by the body mass of the herbivore, with small herbivores selecting for high-quality forage, and with increasing body mass animals are less selective. Several theories attempt to explain and quantify the relationship between animals and their food, such as Kleiber's law , Holling's disk equation and the marginal value theorem (see below). Kleiber's law describes the relationship between an animal's size and its feeding strategy, saying that larger animals need to eat less food per unit weight than smaller animals. Kleiber's law states that
2436-783: Is irrelevant and derived to explain trends that do not exist in nature. Holling's disk equation models the efficiency at which predators consume prey. The model predicts that as the number of prey increases, the amount of time predators spend handling prey also increases, and therefore the efficiency of the predator decreases. In 1959, S. Holling proposed an equation to model the rate of return for an optimal diet: Rate (R )=Energy gained in foraging (Ef)/(time searching (Ts) + time handling (Th)) R = E f / ( T s + T h ) {\displaystyle R=Ef/(Ts+Th)} Where s=cost of search per unit time f=rate of encounter with items, h=handling time, e=energy gained per encounter. In effect, this would indicate that
2523-455: Is long and lacks an obturator projection on the anterior margin. The ischia are not fused together at their distal ends. The ischium tapers downwards with a slight bend forward halfway through. Nothing of the pubic bones has been found. The thighbones are only slightly longer than the shinbones. In this, Stegouros is closer to running ancestors who had a noticeably shorter femur. Later Ankylosauria typically have very short lower legs. The femur
2610-456: Is not made up of fused ossicles. Two pairs of small cone-shaped osteoderms with pointed keels and concave lower surfaces are present at the base of the tail. Very distinctive is the so-called "tail weapon". Ankylosaurids typically have a tail club but the Stegouros weapon has a very distinct build, representing a type not yet known from Ankylosauria. It has been compared by the describers to
2697-432: Is probably proportionally large, though it is difficult to precisely gauge the proportions due to limited preservation. The praemaxillae of the front snout are toothless, short, high and narrow, and completely fused at the midline. The front palate to which they contribute is high. The maxillary bones merge seamlessly into the plate-shaped lacrimal bones that slope backwards. The maxillary bones have internal branches that form
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2784-416: Is straight and not bent as in running forms. The fourth trochanter, the protrusion on the posterior femoral shaft that served to attach the tail retractor muscle, is small and shaped like a vertical ridge. The lesser trochanter is fused with the greater trochanter. As with running forms, the feet are quite narrow. The third and fourth metatarsal bones have long contact surfaces at the top. This indicates that
2871-488: Is the ability of a plant to withstand damage without a reduction in fitness. This can occur by diverting herbivory to non-essential plant parts, resource allocation, compensatory growth, or by rapid regrowth and recovery from herbivory. Resistance refers to the ability of a plant to reduce the amount of damage it receives from herbivores. This can occur via avoidance in space or time, physical defenses, or chemical defenses. Defenses can either be constitutive, always present in
2958-592: The Northern Hemisphere ( North America , Europe and Asia ), but the more basal Parankylosauria are known from southern Gondwana ( South America , Australia and Antarctica ) during the Cretaceous. Ankylosauria was first named by Henry Fairfield Osborn in 1923. In the Linnaean classification system, the group is usually considered either a suborder or an infraorder. It is contained within
3045-554: The PhyloCode . Phylogenetic and morphological studies have differed on the inclusion of certain early taxa into Ankylosauria, especially the armoured Early Jurassic form Scelidosaurus . As some analyses, like that of Carpenter from 2001 or David B. Norman in 2021 find Scelidosaurus and possibly other early forms like Emausaurus and Scutellosaurus to fall closer to Ankylosaurus than Stegosaurus , Carpenter and later Norman suggested redefining Ankylosauria to limit it to
3132-491: The cellulose in plants, whose heavily cross-linking polymer structure makes it far more difficult to digest than the protein - and fat -rich animal tissues that carnivores eat. Herbivore is the anglicized form of a modern Latin coinage, herbivora , cited in Charles Lyell 's 1830 Principles of Geology . Richard Owen employed the anglicized term in an 1854 work on fossil teeth and skeletons. Herbivora
3219-566: The maquahuitl , the Aztec mace. The weapon consists of seven pairs of flattened osteoderms that form an elongated structure that covers the tip of the tail. The first pair has sharp keels, the tips of which point towards the rear and sides. Their upper surfaces are, apart from that, more flattened while the lower sides are more conically curved. The inner sides, facing the tail vertebra, are strongly hollowed out. On their undersides are two pairs of smaller cone-shaped osteoderms fused, resembling those on
3306-432: The wetland ecosystem . Such differences in herbivore modalities can potentially lead to trade-offs that influence species traits and may lead to additive effects on community composition and ecosystem functioning. Seasonal changes and environmental gradients such as elevation and latitude often affect the palatability of plants which in turn influences herbivore community assemblages and vice versa. Examples include
3393-698: The Cretaceous of southern Gondwana, also including Kunbarrasaurus from Australia and Antarctopelta from the Antarctic Peninsula . diverging before Ankylosauridae and Nodosauridae together, which was named Parankylosauria . The results of this phylogenetic analysis are shown below: Lesothosaurus Scutellosaurus Emausaurus Scelidosaurus Huayangosaurus Stegosauridae Kunbarrasaurus Antarctopelta Stegouros Nodosauridae Liaoningosaurus Gobisaurus Shamosaurus Ankylosaurinae The discovery of Stegouros has an important implication for
3480-515: The U.S. Herbivores also affect economics through the revenue generated by hunting and ecotourism. For example, the hunting of herbivorous game species such as white-tailed deer, cottontail rabbits, antelope, and elk in the U.S. contributes greatly to the billion-dollar annually, hunting industry. Ecotourism is a major source of revenue, particularly in Africa, where many large mammalian herbivores such as elephants, zebras, and giraffes help to bring in
3567-491: The back that project caudolaterally. Osteoderms of the head were not found. It may be that those in Stegouros did not ossify or that the individual of the holotype was not old enough to have completed ossification. At the second cervical vertebra, the axis, a flat bone plate with a length of nineteen millimeters was found. Apart from this, no large elements of the neck, such as cervical halfrings, were recovered. Eight medium-sized scutes have been found, oval and keeled with
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3654-416: The balance between eating all the food in a patch for immediate energy, or moving to a new patch and leaving the plants in the first patch to regenerate for future use. The theory predicts that absent complicating factors, an animal should leave a resource patch when the rate of payoff (amount of food) falls below the average rate of payoff for the entire area. According to this theory, an animal should move to
3741-824: The colonization and community assembly of herbivores, and there is evidence of phylogenetic linkage between plant beta diversity and phylogenetic beta diversity of insect clades such as butterflies . These types of eco-evolutionary feedbacks between plants and herbivores are likely the main driving force behind plant and herbivore diversity. Abiotic factors such as climate and biogeographical features also impact plant-herbivore communities and interactions. For example, in temperate freshwater wetlands herbivorous waterfowl communities change according to season, with species that eat above-ground vegetation being abundant during summer, and species that forage below-ground being present in winter months. These seasonal herbivore communities differ in both their assemblage and functions within
3828-778: The early history of ankylosaurians ; it revealed that a novelly discovered, distinct lineage of ankylosaurs , the Parankylosauria , exist, diverging from Euankylosauria (the combined clade of Ankylosauridae and Nodosauridae ) very early in the Cretaceous and surviving until the Maastrichtian , distinguished by a unique tail weapon, dubbed ' macuahuitl ', evolved convergently to ankylosaurid tail clubs. It also suggests, through phylogenetic bracketing , that two genera found to be related by analyses by Soto-Acuña et al. ( Antarctopelta and Kunbarrasaurus ) possessed
3915-424: The effectiveness of plant defenses activated by sunlight. A plant defense is a trait that increases plant fitness when faced with herbivory. This is measured relative to another plant that lacks the defensive trait. Plant defenses increase survival and/or reproduction (fitness) of plants under pressure of predation from herbivores. Defense can be divided into two main categories, tolerance and resistance. Tolerance
4002-515: The eighteenth vertebra, all the vertebrae are missing: only the cavity within the macuahuitl gives an indication of how many were present. The authors estimate the maximum number of these to be eight, which would imply that there were only twenty-six tail vertebrae; the lowest number in all of Thyreophora was thirty-five until 2021, in Scelidosaurus . The vertebrae of the tail are amphiplatyan to platycoel: flat on both ends or slightly concave at
4089-538: The end of that period. Herbivory among four-limbed terrestrial vertebrates, the tetrapods , developed in the Late Carboniferous (307–299 million years ago). The oldest known example being Desmatodon hesperis. Early tetrapods were large amphibious piscivores . While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types, tetrapods (carnivory) and plants (herbivory). The entire dinosaur order ornithischia
4176-510: The equivalent of millions of US dollars to various nations annually. Stegouros Stegouros ( / ˌ s t ɛ ɡ ə ˈ jʊər ɒ s / , meaning "roofed tail") is a genus of ankylosaurian dinosaur from the Late Cretaceous Dorotea Formation of southern Chile . The genus contains a single species, Stegouros elengassen , known from a semi-articulated, near-complete skeleton. In February 2018,
4263-406: The first informal definition of the group, as all ornithischians closer to Ankylosaurus than Stegosaurus . This definition was further refined by Paul Sereno in 2005 to specify Ankylosaurus magniventris and Stegosaurus stenops , the type species of both genera, a definition that was followed by Madzia and colleagues in 2021 when the group name and definition was formalized following
4350-493: The first land plants evolved. Insects fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a "pierce and suck" technique. During the next 75 million years , plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian , 330.9 million years ago . There
4437-596: The food chain because they consume plants to digest the carbohydrates photosynthetically produced by a plant. Carnivores in turn consume herbivores for the same reason, while omnivores can obtain their nutrients from either plants or animals. Due to a herbivore's ability to survive solely on tough and fibrous plant matter, they are termed the primary consumers in the food cycle (chain). Herbivory, carnivory, and omnivory can be regarded as special cases of consumer–resource interactions . Two herbivore feeding strategies are grazing (e.g. cows) and browsing (e.g. moose). For
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#17327901695494524-565: The food source, in this case, the plant. Several factors play into these fluctuating populations and help stabilize predator-prey dynamics. For example, spatial heterogeneity is maintained, which means there will always be pockets of plants not found by herbivores. This stabilizing dynamic plays an especially important role for specialist herbivores that feed on one species of plant and prevents these specialists from wiping out their food source. Prey defenses also help stabilize predator-prey dynamics, and for more information on these relationships see
4611-426: The forested habitat and its interaction with other deer while in that habitat. This model has been criticized as circular and untestable. Critics have pointed out that its proponents use examples that fit the theory, but do not use the model when it does not fit the reality. Other critics point out that animals do not have the ability to assess and maximize their potential gains, therefore the optimal foraging theory
4698-439: The fossil preserves. The dentary teeth are leaf-shaped and high. The teeth are asymmetrical in external view. They have a convex cingulum that extends upwards into fluted ridges ending in serrations. The cingulum is asymmetrical: horizontal when seen from the outside but an arc seen viewed the inside, that is slightly oblique towards the front. The cervical vertebrae are short. The vertebral centra are wider than they are long,
4785-832: The fossil record of their jaws near the Permio-Carboniferous boundary, approximately 300 million years ago. The earliest evidence of their herbivory has been attributed to dental occlusion , the process in which teeth from the upper jaw come in contact with teeth in the lower jaw is present. The evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores. This suggests that evolution and spread occurred simultaneously within various lineages. Herbivores form an important link in
4872-409: The group Thyreophora , which also includes the stegosaurs , armored dinosaurs known for their combination of plates and spikes. The name of this group of dinosaurs is associated with a number of anatomical features in which small and large bony shields fused together, completely covering their back and sides. On the skull these shields fused with the underlying bones, and the dorsal ribs fit snugly to
4959-414: The hindlimbs, sacrum, pelvis and tail, was preserved articulated. The front parts were scattered over a small surface. It lacks the skull roof, the rear lower jaws, the shoulder blades, the right humerus and the pubic bones. Some osteoderms were recovered. It represents an adult individual. Stegouros is a very small ankylosaur. It was estimated at to be about 1.8–2 metres (5.9–6.6 ft) long. Only
5046-435: The ilium with short ribs but are not fused to it. At the rear, the sacrum lacks caudosacrals, a basal feature shared with Antarctopelta . The humerus has a slender shaft, a basal feature. However, the ends are strongly transversely broadened, especially in the epiphyses, and there is a well-developed deltopectoral crest projecting anteriorly. On the outer posterior margin of the humerus, a conspicuous ridge runs downwards with
5133-430: The incorporation of silica into cell walls is analogous to that of the role of lignin in that it is a compression-resistant structural component of cell walls; so that plants with their cell walls impregnated with silica are thereby afforded a measure of protection against herbivory. Chemical defenses are secondary metabolites produced by the plant that deter herbivory. There are a wide variety of these in nature and
5220-406: The interaction of herbivory and plant defense is negative, with one individual reducing the fitness of the other, some is beneficial. This beneficial herbivory takes the form of mutualisms in which both partners benefit in some way from the interaction. Seed dispersal by herbivores and pollination are two forms of mutualistic herbivory in which the herbivore receives a food resource and the plant
5307-510: The lateral braincase, the basisphenoid is short, shorter than the basioccipital of the lower occiput. In the lower jaws, the central predentary, the bony core of the lower bill, is short and high with thin upper branches that are longer than the lower branches. The dentarium or os dentale is undulating in side view. The row of teeth is curved inwards, so that the rows of teeth of the lower jaws combined show an hourglass shape when viewed from above. The dentarium bears fourteen teeth, some of which
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#17327901695495394-407: The metabolic rate (q 0 ) of an animal is the mass of the animal (M) raised to the 3/4 power: q 0 =M Therefore, the mass of the animal increases at a faster rate than the metabolic rate. Herbivores employ numerous types of feeding strategies. Many herbivores do not fall into one specific feeding strategy, but employ several strategies and eat a variety of plant parts. Optimal foraging theory
5481-486: The midfoot was not spread out to support the weight, as is the case with most Ankylosauria and Stegosauria. The number of phalanges has not been reduced. At the third and fourth toes, however, the extreme phalanx is not in the shape of a claw but is a flat disc. Those claws present are shaped like hooves. The shoulder blades (scapulae) were not found. The coracoids are not fused with the shoulder blades. The sternal plates are unfused, and have long lateral tubular processes at
5568-402: The patch quality. Interactions between plants and herbivores can play a prevalent role in ecosystem dynamics such community structure and functional processes. Plant diversity and distribution is often driven by herbivory, and it is likely that trade-offs between plant competitiveness and defensiveness , and between colonization and mortality allow for coexistence between species in
5655-423: The pelvis, the horizontal ilium has a very long and low anterior blade. It curves strongly forwards and to the sides, apparently to support a wide abdominal cavity. The rest of the ilium is very similar to that of the Stegosauria. The position and shape of the horizontal lateral ridge above the hip joint, i.e. semicircular, and the shape of the rear blade suggest that the latter turned inward during growth. The ischium
5742-570: The plant, or induced, produced or translocated by the plant following damage or stress. Physical, or mechanical, defenses are barriers or structures designed to deter herbivores or reduce intake rates, lowering overall herbivory. Thorns such as those found on roses or acacia trees are one example, as are the spines on a cactus. Smaller hairs known as trichomes may cover leaves or stems and are especially effective against invertebrate herbivores. In addition, some plants have waxes or resins that alter their texture, making them difficult to eat. Also
5829-547: The posterior vertebra. This system must have stiffened the tail tip. However, no ossified tendons are used for this as with the Ankylosauridae, because they are completely lacking. Flattened vertebrae have also been found in Antarctopelta , suggesting that a similar tail weapon was present in that species. Stegouros was found by Soto-Acuña et al. to belong to a distinct lineage of small ankylosaurs known from
5916-538: The presence of herbivores. However, the effects of herbivory on plant diversity and richness is variable. For example, increased abundance of herbivores such as deer decrease plant diversity and species richness , while other large mammalian herbivores like bison control dominant species which allows other species to flourish. Plant-herbivore interactions can also operate so that plant communities mediate herbivore communities. Plant communities that are more diverse typically sustain greater herbivore richness by providing
6003-403: The production of large amounts of saliva to reduce effectiveness of defenses. Herbivores may also utilize symbionts to evade plant defenses. For example, some aphids use bacteria in their gut to provide essential amino acids lacking in their sap diet. Plant modification occurs when herbivores manipulate their plant prey to increase feeding. For example, some caterpillars roll leaves to reduce
6090-411: The rear. The lateral processes are long, twice longer than the neural spines, and are still present as far as the tail weapon. In the seventh through twelfth vertebrae, the neural spines are somewhat thickened at the top and shorter than the neural arches. Behind the twelfth vertebra, the undersides have a longitudinal groove and are as long as they are wide but very low. The inner cavity of the tail weapon
6177-545: The roof-like covering of the tail end. The specific name elengassen is derived from an armoured creature in the mythology of the Aónik’enk , the indigenous inhabitants of the region where the holotype was discovered. The holotype , CPAP-3165 , was found in a layer of the Dorotea Formation dating from the upper Campanian . It consists of a relatively complete skeleton with skull and lower jaws. The rear part,
6264-424: The sacral vertebrae, absence of ossified tendons on the tail, teeth with six serrations on the anterior margin instead of seven or eight, and cingula , thickened tooth crown bases, without vertical grooves. Stegouros differs from Kunbarrasaurus by having a curved instead of straight ulna and radius and a process from the maxilla running towards the lacrimal bone that is narrower and sloping backwards. The head
6351-490: The section on Plant Defenses. Eating a second prey type helps herbivores' populations stabilize. Alternating between two or more plant types provides population stability for the herbivore, while the populations of the plants oscillate. This plays an important role for generalist herbivores that eat a variety of plants. Keystone herbivores keep vegetation populations in check and allow for a greater diversity of both herbivores and plants. When an invasive herbivore or plant enters
6438-556: The size of herbivores having an effect on the amount of energy intake that is needed, larger herbivores need to forage on higher quality or more plants to gain the optimal amount of nutrients and energy compared to smaller herbivores. Environmental degradation from white-tailed deer ( Odocoileus virginianus ) in the US alone has the potential to both change vegetative communities through over-browsing and cost forest restoration projects upwards of $ 750 million annually. Another example of
6525-583: The skeleton of a small ankylosaur was recovered by a team of Texan researchers near the Río de las Chinas valley of Ultima Esperanza province in the Magallanes y la Antártica Chilena region of southern Chile. In 2021, the type species Stegouros elengassen was named and described by Sergio Soto-Acuña et al . The generic name combines the Greek stegos , meaning "roof" and oura , meaning "tail", referring to
6612-453: The system, the balance is thrown off and the diversity can collapse to a monotaxon system. The back and forth relationship of plant defense and herbivore offense drives coevolution between plants and herbivores, resulting in a "coevolutionary arms race". The escape and radiation mechanisms for coevolution, presents the idea that adaptations in herbivores and their host plants, has been the driving force behind speciation . While much of
6699-442: The tail base, one pair pointing obliquely to the rear and the other obliquely sideways and downwards. The next pair is larger and covers two entire vertebrae. It is flatter and lacks the small osteoderms on the underside. The construction of the next five pairs is similar, but they have grown together with their leading and trailing edges to form one whole. They are still separately recognizable as pentagonal plates with pointed ends. At
6786-503: The tail was considered to be strictly distinctive. Unlike all other known Ankylosauria, the tail is short with no more than twenty-six caudal vertebrae, the last twelve of which are covered by seven pairs of large osteoderms, the last five of which again are fused together to form a flat connected structure. Stegouros differs from its close relative Antarctopelta in its smaller body size, relatively larger neural canal, longer dorsosacral vertebrae, higher and narrower vertebral bodies of
6873-485: The theme. The understanding of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defence (such as spines), or herbivory-related damage; the observation of plant debris in fossilised animal faeces ; and the construction of herbivore mouthparts. Although herbivory was long thought to be a Mesozoic phenomenon, fossils have shown that plants were being consumed by arthropods within less than 20 million years after
6960-421: The theory of predator –prey interactions, the relationship between herbivores and plants is cyclic. When prey (plants) are numerous their predators (herbivores) increase in numbers, reducing the prey population, which in turn causes predator number to decline. The prey population eventually recovers, starting a new cycle. This suggests that the population of the herbivore fluctuates around the carrying capacity of
7047-576: The traditional Ankylosauridae-Nodosauridae split, instead finding "nodosaurids" to be referrable to three separate families: Panoplosauridae , Polacanthidae , and Struthiosauridae . Sarcolestes Paw Paw juvenile Animantarx Cedarpelta Gargoyleosaurus Hoplitosaurus Niobrarasaurus Polacanthus Texasetes Patagopelta Hylaeosaurus Gastonia burgei Gastonia lorriemcwhinneyae Peloroplites Sauropelta Tatankacephalus Invictarx Silvisaurus Herbivorous A herbivore
7134-413: The two subclades Nodosauridae and Ankylosauridae , creating the new clade Ankylosauromorpha for all taxa closer to Ankylosaurus than Stegosaurus . However, as historically even these primitive forms were considered ankylosaurs if they were more derived than Stegosaurus , Madzia and colleagues considered a redefinition of Ankylosauria to be undesirable, instead preferring to abandon Ankylosauromorpha as
7221-543: The upper right ulna is a small round bone plate, keeled with a concave inner surface, next to a flat triangular osteoderm. Keeled osteoderms were found on the outside of the feet, three on the left foot and two on the right foot. Between the ilium and the neural spines of the sacrum is a continuous thin layer of ossified skin armor covered with vein grooves and pits. This indicates the presence of some kind of sacral shield as in Nodosauridae. However, it differs in that it
7308-400: The vertebrae. The Latin name Ankylosauria is derived from the Greek ἀγκύλος [ankylos] — "curved", "bent" with the anatomical meaning "hard" or "fused" and σαῦρος [sauros] — "lizard". In the 1908 description of the genus Ankylosaurus , Barnum Brown described the family Ankylosauridae as a group of representatives with a "rigid spine", but noted the wide, curved shape of the ribs, suggesting
7395-412: The very end, this structure also covers the undersides of the vertebrae. At the extreme tail tip is an eighth pair of small knob-shaped osteoderms. Numerous ossicles in the form of circular disks, four to five millimeters in diameter, were found around all skeletal elements. They are flattened into an oblate spheroid with an almost square profile. The outer sides are covered with numerous pits, indicating
7482-429: Was a gap of 50 to 100 million years between the time each organ evolved and the time organisms evolved to feed upon them; this may be due to the low levels of oxygen during this period, which may have suppressed evolution. Further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonization are recorded in the early Permian , with surface fluid feeding evolving by
7569-431: Was composed of herbivorous dinosaurs. Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation. In contrast, a complex set of adaptations was necessary for feeding on highly fibrous plant materials. Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities. Tetrapod herbivores made their first appearance in
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