Fossil: Mammal attacks dinosaur - Canadian Museum of Nature
The fossil sowing the entangled skeletons of the dinosaur (Psittacosaurus) and the mammal (Repenomamus). Scale bar equals 10 cm.
This is how we can tell that their favourite source book is worthless as an account of real science, biology, geography and history. It is quite simply demonstrably and unarguably so wrong about just about everything, as we now know, that it's laughable that grown adults believe any of it.
Q: How do we know that early mammals were preying on dinosaurs 125 million years ago?
A: Because we have the evidence.
It comes in the form of a fossil of an early mammal attacking a dinosaur, dated to 125 million years old, as described in a paper published in the journal Scientific Reports. The fossil shows a (smaller) mammal in the process of attacking or maybe even eating alive, a (larger) dinosaur. The pair were suddenly engulfed in a volcanic debris flow.
As a news release from the Canadian Museum of Nature explains:
The fossil’s presence challenges the view that dinosaurs had few threats from their mammal contemporaries during the Cretaceous, when dinosaurs were the dominant animals. The rare fossil is now in the collections of the Weihai Ziguang Shi Yan School Museum in China’s Shandong Province.The open access paper in Scientific Reports gives more details:
The dinosaur in the well-preserved fossil is identified as a species of Psittacosaurus, which is about the size of a large dog. Plant-eating psittacosaurs are among the earliest known horned dinosaurs and lived in Asia during the Early Cretaceous, from around 125 to 105 million years ago.
The mammal in the fossil pair is a badger-like animal, called Repenomamus robustus. Although not large by dinosaur standards, it was among the largest mammals during the Cretaceous, at a time when mammals had not yet come to dominate the Earth.
Prior to this discovery, palaeontologists knew that Repenomamus preyed on dinosaurs including Psittacosaurus because of fossilized baby bones of the herbivore found in the mammal’s stomach.
“The co-existence of these two animals is not new, but what’s new to science through this amazing fossil is the predatory behaviour it shows,” says Mallon.
The fossil was collected in China’s Liaoning Province in 2012, and both skeletons are nearly complete. Their completeness is due to the fact that they come from an area known as the Liujitun fossil beds, which have been dubbed “China’s Dinosaur Pompeii”.
Hillside where the fossil was collected in 2012 from the Lujiatun Member of the Yixian Formation of northeastern China.
The name refers to the many fossils of dinosaurs, small mammals, lizards and amphibians in the area, animals that were buried suddenly en masse by mudslides and debris following one or more volcanic eruptions. The existence of volcanic material in the rock matrix of the study’s fossil was confirmed following analysis by Canadian Museum of Nature mineralogist Dr. Aaron Lussier.
A close examination of the fossil pair shows that the Psittacosaurus is lying prone, with its hindlimbs folded on either side of its body. The body of the Repenomamus coils to the right and sits atop its prey, with the mammal gripping the jaw of the larger dinosaur. The mammal is also biting into some of the ribs, and the back foot of Repenomamus is gripping onto the dino’s hind leg. “The weight of the evidence suggests that an active attack was underway,” says Dr. Mallon.
Mallon, Wu and colleagues ruled out the possibility that the mammal was simply scavenging a dead dinosaur. The bones of the dinosaur have no tooth marks, for example, suggesting it was not being scavenged, but rather was being preyed upon. And it’s unlikely the two animals would have become so entangled if the dinosaur had been dead before the mammal came upon it. The position of the Repenomamus over top of the Psittacosaurus suggests it was also the aggressor.
Fossil with the entangled skeletons of Psittacosaurus and Repenomamus showing details of their interaction.
Detail of fossil showing Repenomamus biting the ribs of Psittacosaurus.
Detail of fossil showing the left hand of Repenomamus wrapped around the lower jaw of Psittacosaurus.
Analogies of smaller animals attacking larger prey are known in the modern world. Mallon and Wu note that some lone wolverines are known to hunt larger animals, including caribou and domestic sheep. And on the African savanna, wild dogs, jackals and hyenas will attack prey that are still alive, with the prey collapsing, often in a state of shock.
“This might be the case of what’s depicted in the fossil, with the Repenomamus actually eating the Psittacosaurus while it was still alive—before both were killed in the roily aftermath,” explains Mallon.
The research team speculates in their paper that the volcanically derived deposits from the Lujiatun fossil beds in China will continue to yield new evidence of interactions among species, otherwise unknown from the rest of the fossil record.
AbstractAt the risk of making creationists cry, I'll point out that the dating method used is U-Pb (uranium/lead) in tuffaceous (i.e., volcanic in origin) zircons. This is one of the most accurate dating methods, based on the fact that a small amount of radioactive uranium (238U and 235U gets included in zircon crystals which form in volcanic lava. 238U has a half-life of about 4.5 billion years and 235U has a half-life of 700 million years. These both decay into lead, locked within the crystal lattice, which could not have been incorporated into zircon crystals any other way, and there is no mechanism by which it could leach out, so by measuring the amount of lead and the amount of uranium in the zircon crystals, the age of the zirconium crystals and the volcanic rock they formed in, can be calculated.
Dinosaurs and mammals have coexisted for the last ~ 230 million years. Both groups arose during the Late Triassic and diversified throughout the Mesozoic and into the Cenozoic (the latter in the form of birds). Although they undoubtedly interacted in many ways, direct fossil evidence for their interaction is rare. Here we report a new fossil find from the Lujiatun Member of the Lower Cretaceous Yixian Formation of China, showing a gobiconodontid mammal and psittacosaurid dinosaur locked in mortal combat. We entertain various hypothesized explanations for this association, but the balance of the evidence suggests that it represents a predation attempt on the part of the smaller mammal, suddenly interrupted by, and preserved within, a lahar-type volcanic debris flow. Mesozoic mammals are usually depicted as having lived in the shadows of their larger dinosaurian contemporaries, but this new fossil convincingly demonstrates that mammals could pose a threat even to near fully-grown dinosaurs. The Yixian Formation—and the Chinese fossil Jehol Biota more broadly—have played a particularly important role in revealing the diversity of small-bodied dinosaurs and other fauna. We anticipate that the volcanically derived obrution deposits specific to the Lujiatun Member will likewise continue to yield evidence for biotic interactions otherwise unknown from the rest of the fossil record.
Introduction
For nearly 230 million years, mammals and dinosaurs have been among the most successful vertebrate groups on Earth. Each group originated in the Late Triassic and has since diversified into the myriad of forms known today (dinosaurs in the form of birds, following the end-Cretaceous mass extinction). Mesozoic mammals are commonly depicted as having lived in the shadows of their larger dinosaurian contemporaries, and dinosaur gut contents containing the remains of small mammals bear this out1,2,3. It was not until after the end-Cretaceous extinction of the non-avian dinosaurs that mammals grew to large body sizes and regularly preyed on the available avifauna.
Dinosaur-mammal antagonism during the Mesozoic was not strictly unilateral, however. Fossil gut contents of the Chinese gobiconodontid mammal Repenomamus robustus contain the remains of a much smaller, perinatal Psittacosaurus sp.4, an early ceratopsian dinosaur. Here we report on a yet more exceptional discovery preserving these two genera locked in mortal combat—the first such fossil of its kind. The new fossil (Weihai Ziguang Shi Yan School Museum WZSSM] specimen VF000011) was discovered on May 16, 2012 west of Lujiatun Village in Liaoning Province, near coordinates N41°36′24″, E120°54′40″ (Supplementary Fig. S1). It was acquired by the first author and donated to the WZSSM in 2020. The fossil originates from the Lujiatun Member of the Yixian Formation, the latter being 212 m thick locally. The Lujiatun Member is famous for its abundance of vertebrate fossils, especially the fossils of Psittacosaurus lujiatunensis, whose uncorrected relative abundance reaches nearly 90%, locally5. The sediments there are volcanically derived, and although depositional age estimates have varied6,7, the latest U–Pb dating of tuffaceous zircons indicates an age between 125.755 &plusmmn; 0.061 and 125.684 ± 0.060 Ma8.
The only way this dating method could be wrong to the extent that it makes 10,000 years look like 125 million years would be if the decay rates of 238U and 235U were so massively different that it would now take 125 million years for the same number of atoms of 238U and 235U to decay to lead as decayed in the previous 10,000 years, which would mean the weak and strong nuclear forces were so much weaker then that atoms could not have existed when creationists believe the universe was magicked out of nothing, so stars, planets, minerals, rocks and life itself would not have been possible. The universe would have consisted of elementary particles and electromagnetic radiation and nothing else.
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