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Extinct Animal News (Except Dinosaurs)

Italy Ngala Offline
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#76
( This post was last modified: 09-01-2017, 08:55 PM by Ngala )

Xibalbaonyx oviceps, a new megalonychid ground sloth (Folivora, Xenarthra) from the Late Pleistocene of the Yucatán Peninsula, Mexico, and its paleobiogeographic significance
Xibalbaonyx oviceps Stinnesbeck et al., 2017

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*This image is copyright of its original author

Fig. 3: Xibalbaonyx oviceps in situ within the Zapote cenote; Skull and mandible (Za2014-01, -05)

Abstract:
"Here we describe a new genus and species of giant ground sloth, Xibalbaonyx oviceps (Megalonychidae, Xenarthra), from the drowned cave system of the northeastern Yucatán Peninsula. The specimen is Late Pleistocene in age and was discovered in the Zapote sinkhole (cenote) near Puerto Morelos in the Mexican state of Quintana Roo. Xibalbaonyx oviceps differs significantly from all hitherto known Megalonychidae including those from the Greater Antilles and South America. The new taxon suggests a local Caribbean radiation of ground sloths during the Late Pleistocene, which is consistent with the dispersal of the group along a Mexican corridor."

Other articles related:
Ancient species of giant sloth discovered in Mexico
"Man still bears in his bodily frame the indelible stamp of his lowly origin." C. Darwin
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Venezuela epaiva Online
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#77

(11-06-2016, 04:33 PM)Ngala Wrote: Giant extinct salmon fought with spike teeth during upriver spawning events
October 28, 2016

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An illustration by Jacob Biewer Credit: Society of Vertebrate Paleontology

The ancient coastal waters of the Pacific, roughly 11 to 5 million years ago, were home to a bizarre and fascinating species of giant salmon with large spike-like teeth. This spike-toothed salmon reached sizes of 3 to 9 feet in length (1-3 meters), much larger than the typical salmon found in the Pacific today. These hefty spike-toothed fish would have made for a difficult catch at nearly 400 pounds (177 kg). The spike-like teeth of the salmon could be over an inch long (3 cm), much longer than modern Pacific salmon teeth, even after compensating for their larger size. Researchers from California State University in Turlock, California have been studying the strange teeth of these unusual fish and discovered some tantalizing clues into their past behavior and life history.

Much like modern Pacific salmon, the giant salmon was likely primarily a filter-feeder, so the spike teeth were probably not part of catching prey. Modern salmon go through physical changes in their body, especially their skull, before migrating upriver to spawn where males will fight to defend the eggs they have fertilized. To see if these teeth played an important role in breeding of the giant fossil salmon, the team of researchers, led by Dr. Julia Sankey, compared 51 different fossils from ancient deposits of both freshwater and saltwater environments. The teeth of these salmon found in past freshwater environments consistently had longer, more recurved teeth with much larger bases, as well as showed clear signs of wear. Fossil salmon teeth from saltwater deposits were much smaller and less worn. This indicates that they changed prior to migration upriver to spawn.

These results help show that these impressive spike-like teeth of the giant salmon are indeed used as part of the breeding process in these extinct fish. Researchers think it is likely these hefty bruisers were using their spike-like teeth for fighting and display against each other during the spawning season, up in the ancient rivers of California. "These giant, spike-toothed salmon were amazing fish. You can picture them getting scooped out of the Proto-Tuolumne River [near Modesto, California] by large bears 5 million years ago." said Dr. Sankey "Scientifically, our research on the giant salmon is filling in a gap in our knowledge about how these salmon lived, and specifically, if they developmentally changed prior to migration upriver like modern salmon do today. This research is also helping paint the picture of this area 5 million years ago for the general public and my college students, and it excites them to think of this giant salmon swimming up our local rivers 5 million years ago!". Dr.Sankey and colleagues presented their research at this year's meeting of the Society of Vertebrate Paleontology in Salt Lake City, Utah.

*This image is copyright of its original author

An illustration by Jacob Biewer. Credit: Society of Vertebrate Paleontology
Incredible Giant Salmon
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Canada HyperNova Offline
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Giganthopithecus blacki size has been vastly exagerrated.

''Given the very large size of the cheek teeth and massiveness of the mandible it can be presumed that G. blacki was larger than any living hominoid, including extant gorillas (with an average male body weight of 169 kg; Smith & Jungers, 1987). Weidenreich (1945) speculated that it was twice the size of Gorilla. Others have proposed an estimated body mass of 225–300 kg (Ciochon et al., 1990; Dean & Schrenk, 2003; Fleagle, 2013; Simons, 1972; Simons & Ettel, 1970) and a standing height of 9–12 ft (2.7–3.7 m) (Ciochon et al., 1990; Pei, 1957b; Simons, 1972). Johnson (1979) argued that the limb bones of G. blacki would have been 20–25% larger than those of extant gorillas. Based on M1area to body mass correlations (Conroy, 1987; Gingerich, Smith, & Rosenberg, 1982), we are able to calculate an estimated body mass of 204 kg (using the Gingerich formula) and 280 kg (using the Conroy formula for apes). Obviously, the use of dental size as a predictor of body mass in fossil primates is problematic because dental size varies considerably within any body size class for a variety of functional and phylogenetic factors (Delson et al., 2000). Nevertheless, one might make a reasonable case from what is known about its anatomy that G. blacki was likely to have been a relatively megadont hominoid, and that any body mass prediction based on molar size will probably represent an overestimation. Without postcranial remains it is simply not possible to obtain a reliable estimate of the body mass for G. blacki, but 200–300 kg does seem like a reasonable guide. Such a size (which overlaps with the upper end of the body mass range for extant male gorillas) may have precluded or greatly restricted arboreal behaviors in G. blacki, but once again postcranial remains are needed in order to determine its inferred locomotor repertoire.''

Source : Gigantopithecus blacki: a giant ape from the Pleistocene of Asia revisited
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Italy Ngala Offline
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( This post was last modified: 09-08-2017, 05:05 PM by Ngala )

A Devonian tetrapod-like fish reveals substantial parallelism in stem tetrapod evolution 
Hongyu chowi Zhu et al., 2017

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Fig. 4 - Life restoration. Hongyu chowi gen. et sp. nov. and associated antiarchs (Ningxialepis spinosa) from the Zhongning Formation (Famennian, Late Devonian period), Ningxia, China. Illustration: B. Choo.

Abstract:
"The fossils assigned to the tetrapod stem group document the evolution of terrestrial vertebrates from lobe-finned fishes. During the past 18 years the phylogenetic structure of this stem group has remained remarkably stable, even when accommodating new discoveries such as the earliest known stem tetrapod Tungsenia and the elpistostegid (fish–tetrapod intermediate) Tiktaalik. Here we present a large lobe-finned fish from the Late Devonian period of China that disrupts this stability. It combines characteristics of rhizodont fishes (supposedly a basal branch in the stem group, distant from tetrapods) with derived elpistostegid-like and tetrapod-like characters. This mélange of characters may reflect either detailed convergence between rhizodonts and elpistostegids plus tetrapods, under a phylogenetic scenario deduced from Bayesian inference analysis, or a previously unrecognized close relationship between these groups, as supported by maximum parsimony analysis. In either case, the overall result reveals a substantial increase in homoplasy in the tetrapod stem group. It also suggests that ecological diversity and biogeographical provinciality in the tetrapod stem group have been underestimated."

Other articles related:
Weird fish fossil changes the story of how we moved onto land
"Man still bears in his bodily frame the indelible stamp of his lowly origin." C. Darwin
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Italy Ngala Offline
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( This post was last modified: 09-13-2017, 10:15 PM by Ngala )

An edrioasteroid from the Silurian Herefordshire Lagerstätte of England reveals the nature of the water vascular system in an extinct echinoderm Briggs et al., 2017

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Heropyrgus disterminus. Credit: © Proceedings of the Royal Society B: Biological Sciences (2017).

Abstract:
"Echinoderms are unique in having a water vascular system with tube feet, which perform a variety of functions in living forms. Here, we report the first example of preserved tube feet in an extinct group of echinoderms. The material, from the Silurian Herefordshire Lagerstätte, UK, is assigned to a new genus and species of rhenopyrgid edrioasteroid, Heropyrgus disterminus. The tube feet attach to the inner surface of compound interradial plates and form two sets, an upper and a lower, an arrangement never reported previously in an extant or extinct echinoderm. Cover plates are absent and floor plates are separated creating a large permanent entrance to the interior of the oral area. The tube feet may have captured food particles that entered the oral area and/or enhanced respiration. The pentameral symmetry of the oral surface transitions to eight columns in which the plates are vertically offset resulting in a spiral appearance. This change in symmetry may reflect flexibility in the evolutionary development of the axial and extraxial zones in early echinoderm evolution."

Other articles related:
430-million-year-old extinct echinoderm found in England
"Man still bears in his bodily frame the indelible stamp of his lowly origin." C. Darwin
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Italy Ngala Offline
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A new giraffid (Mammalia, Ruminantia, Pecora) from the late Miocene of Spain, and the evolution of the sivathere-samothere lineage
Decennatherium rex Ríos, Sánchez & Morales, 2017

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Fig 41. Reconstruction of Decennatherium rex sp. nov. from BAT10.
A, skeletal reconstruction; B, life reconstruction of an adult female; C, life reconstruction of the head of an adult female. Illustration by Oscar Sanisidro.

Abstract:
"Giraffids include the only living giraffomorph ruminants and are diagnosed by the presence of bi-lobed canines and a special type of epiphyseal cranial appendages called ossicones. The family Giraffidae ranges from the latest early Miocene until today. However they are currently extant relics with only two living representatives, the African genera Okapia and Giraffa. Giraffids were much more diverse and widespread in the past, with more than 30 fossil species described. For the past decades a number of studies intended to resolve the phylogenetic relationships of the family, but due to the lack of really good cranial material no clear consensus was reached regarding the phylogenetic relationships amongst the different members of the group. The exceptionally complete remains of a new large giraffid from the late Miocene of Spain, Decennatherium rex sp. nov., allows us to improve and reassess giraffid systematics, offering a lot of new data, both anatomic and phylogenetic, on the large late Miocene giraffids of Eurasia. The results of our cladistic analysis show Decennatherium as a basal offshoot of a clade containing the gigantic samotheres and sivatheres, characterized by the presence of a Sivatherium-like ossicone-plan among other features. Decennatherium thus offers the most ancient evidence of this Sivatherium-plan and firmly establishes the early morphological patterns of evolution of a sivathere / samothere-clade that is defined as the less inclusive clade that contains Decennatherium and Sivatherium. Finally, this large group of four-ossiconed giraffids evolutionarily links Miocene Europe and Africa indicating vicariance / migration processes among the giraffid genetic pools separated by the Mediterranean Sea."
"Man still bears in his bodily frame the indelible stamp of his lowly origin." C. Darwin
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Italy Ngala Offline
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Highly derived eutherian mammals from the earliest Cretaceous of southern Britain
Durlstotherium newmani Sweetman, Smith & Martill, 2017
Durlstodon ensomi Sweetman, Smith & Martill, 2017

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Fig. 7. Artist’s impression of the Purbeck lagoon at dusk with Durlstodon gen. nov. (left foreground), Durlstotherium gen. nov. (right and center foreground) and the theropod Nuthetes holding a captured Durlstotherium (centre middle distance). 

Abstract:
"Eutherian mammals (Placentalia and all mammals phylogenetically closer to placentals than to marsupials) comprise the vast majority of extant Mammalia. Among these there is a phenomenal range of forms and sizes, but the origins of crown group placentals are obscure. They lie within the generally tiny mammals of the Mesozoic, represented for the most part by isolated teeth and jaws, and there is strongly conflicting evidence from phenomic and molecular data as to the date of origin of both Eutheria and Placentalia. The oldest purported eutherians are Juramaia from the Upper Jurassic of China, and Eomaia and Acristatherium from the Lower Cretaceous, also of China. Based on dental characters and analyses of other morphological and molecular data, doubt has recently been cast on the eutherian affinities of the Chinese taxa and consequently on the date of emergence of Eutheria. Until now, the only tribosphenic mammal recorded from the earliest Cretaceous (Berriasian) Purbeck Group of Britain was the stem tribosphenidan Tribactonodon. Here we document two new tribosphenic mammals from the Purbeck Group, Durlstotherium gen. nov. and Durlstodon gen. nov., showing highly derived eutherian molar characters that support the early emergence of this clade, prior to the Cretaceous."

Other articles related:
Teeth discovered in Dorset reveal secrets of the origins of modern mammals
"Man still bears in his bodily frame the indelible stamp of his lowly origin." C. Darwin
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United States brotherbear Offline
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Not a dinosaur but rather a giant lizard - https://twilightbeasts.wordpress.com/201...own-under/  
 
The dragon down under
Posted on October 8, 2014 by twilightbeasts
Not so long ago an enormous lizard dragged it claws through the dried, dead leaves deep in the Australian woodlands. Longer than a black cab, this was the largest lizard (so far discovered) ever to walk on land. Its teeth were around 2 inches long, curved back, and as sharp (and as big) as steak knives.
Fossils of this enormous lizard were first discovered in 1859 on the beautiful farmlands of Darling Downs, Queensland in Eastern Australia.  Named by the great Victorian scientist, Richard Owen (is there a beast he didn’t name?), the creature was called Megalania prisca which translates as the ‘roaming lizard’. Today the name of this giant should belong in the same Genus as monitor lizards, like the infamous Komodo Dragon, so should be called Varanus priscus. Both genus names are accepted, although Varanus is preferred. Megalania is accepted as the common name. Taxonomists can be a pernickety bunch sometimes.

This terrifying lizard is only known from a few scattered remains. Skull fragments, teeth, a few arm and leg bones, and vertebrae have been found at several sites across Eastern and Southern Australia. No complete skeleton has yet been found. Isolated fossils have been found in old stream and river bed sediment, and in cave sites: but these were not their natural habitats, the bones ended up there after falling into water or carcases being scavenged and dragged into caves. It is more likely that Megalania trundled through open woodlands and forests.
With such fragmented fossil remains, where Megalania sits within the family of monitor lizards (Varanidae) is difficult to ascertain. These extinct lizards may be closely related to Australia’s largest living lizard, the particularly cute looking perentie; the shape of the top of the skull shares similarities. However, studies of the brain case look like it may be a sister species to the Komodo Dragon. Until more complete specimens are found, the true relationship remains contentious.
As to it’s size, we can make a fairly educated guess by comparing the fossils to skeletons of monitor lizards alive today. This was a massive lizard; bone size calculations compared to other monitor lizards to work out the percentage size difference, place this giant to be somewhere between 4.5 meters and 7 meters. Working out sizes based on a few bones can be problematic, because individuals in populations vary quite dramatically. The Megalania fossils do not represent a fantastically significant sample. However, even based on ‘smaller’ size ranges, it shows that this was one pretty big lizard.

This was a terrifying predator roaming Australia for almost 2 million years. For such an enormous lizard there had to be some pretty big prey around. And there most certainly was. Australia was isolated for over 40 million years since the break up of Gondwana, and the animals there evolved into some incredible forms. During the Pleistocene, the continent was home to a rich and diverse mega-fauna including giant kangaroos, Diprotodon (a kind of massive wombat), and the mihirung (a giant flightless bird). All these strange animals, and many others would have supplied ample food for Megalania. The largest lizard alive today, the Komodo Dragon, has little trouble in taking down massive prey, like water buffalo, and there is no doubt that Megalania would have tackled a Diprotodon with ease. But how could they overcome such big animals?

It was thought that Komodo Dragons had extremely bad dental hygiene resulting in deadly bacteria building up around the rotting flesh stuck to their teeth, resulting in just one bite from this animal causing a slow, and painful death. Komodo Dragons actually have venom glands in their lower jaws. Around 5 glands push venom up, inbetween the teeth; when the Dragon sinks it’s teeth into it’s prey, the venom seeps into the open flesh. It is possible, although not confirmed with fossil evidence, that the huge Megalania also had venom glands: several other species of monitor lizards have venom glands, as well as many other types of lizards. For reptiles, venom makes a lot of sense. Reptiles can move pretty fast, but only in short bursts over small distances; they lack the ability to burn enough continuous energy for a good run. If a reptile can bite and inject venom, the job of seriously wounding (or even killing) it’s prey is done. Megalania may have used this technique, along with ambushing its prey. Fossil footprints preserved at Lake Callabonna, in South Eastern Australia, show evidence of the huge marsupial Diprotodon moving in herds. Animals move in herds for safety. For such large animals like Diprotodons to be travelling in groups means they were protecting themselves from something. Something big.

Contrary to cryptozoologist claims, it appears that this enormous lizard became extinct  about 40,000 years ago. Around this time, Australia’s climate was beginning to get warmer, and drier, resulting in less forested areas. The open lands would have been too hot for such a large lizard to survive in the intense heat (smaller lizards can easily scurry into little crevices for shade). Along with the vanishing safety of the wooded areas, the large herbivores that were once at home here, and also the food for Megalania, began to decline. This extinction coincides with many other of Australia’s mega-fauna. Some animals may have survived in small refugia, pockets where little populations were safe. The arrival of a new hunter, Homo sapiens, may have been the final blow to the big herbivores. And as the prey vanished, so did the last hope for these incredible, unique reptilian giants.

Written by Jan Freedman (@JanFreedman)
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