New Discoveries and Taxonomic Significance
Giant and Dwarf Sauropods of Hațeg Island, Romania
2025-02-15
A UCL research team has discovered two new sauropod species from the Hațeg Basin in Romania, which was the "Hațeg Island" during the Late Cretaceous: Petrustitan hungaricus (approx. 2.5m) and Uriash kadici (over 10m). This discovery shows that even in an isolated island environment, dinosaurs of diverse sizes coexisted, which cannot be explained by the simple "island dwarfism" hypothesis.
The "island dwarfism" hypothesis is an ecological principle stating that large animals living in isolated environments tend to become smaller to adapt to resource constraints.
The "Enigmatic Runner" of the Morrison Formation, Enigmacursor
2025-04-10
The Natural History Museum in London has re-evaluated a previously misclassified fossil from the Morrison Formation in the US and announced a new species of small herbivorous dinosaur, Enigmacursor mollyborthwickae. It lived during the Late Jurassic (about 155 to 148 million years ago) and was a small herbivore, about 1.8m long, 64cm tall at the hip, and weighing about as much as a sheepdog. As its name suggests, it had long legs adapted for running fast, highlighting the diversity of small dinosaurs in the Morrison Formation, which is often noted for its large dinosaurs.
By using digital technology (3D scanning) for comparison, this discovery has prompted a re-evaluation of the classification of other small ornithopods whose classification had long been unclear (especially "Nanosaurus," also found in the Morrison Formation), providing new insights into the evolution of early ornithopods.
The Bizarre Two-Clawed Theropod of Mongolia, Duonychus
2025-06-20
A new species of therizinosaur, Duonychus tsogtbaatari, discovered in the Gobi Desert, had giant claws on only two fingers, unlike its relatives. It lived during the Late Cretaceous (about 95 to 89.6 million years ago). It was a medium-sized herbivorous dinosaur with an estimated weight of about 260 kg.
Notably, the keratin sheaths of the claws were preserved in 3D, suggesting that the claws had an advanced function of "hooking and pulling" branches for feeding on plants. Like other theropods such as tyrannosaurids, Duonychus provides important evidence of finger reduction during evolution.
New Ancestor Fills Gap in Tyrannosaurid Evolution, Khankhuuluu
2025-08-05
A fossil excavated in Mongolia 50 years ago has been reclassified as a new species ancestral to T. rex, Khankhuuluu mongoliensis. Khankhuuluu, which lived in Mongolia about 86 million years ago during the Late Cretaceous, is considered a "missing link" between the small, agile early ancestors of tyrannosaurids and giant apex predators like T. rex.
Khankhuuluu did not yet possess the powerful jaws and bone-crushing ability seen in later tyrannosaurids. It had a more slender skull and razor-like teeth, and is thought to have been a medium-sized predator that hunted prey with speed and agility.
This discovery provides an important "window" into the process by which tyrannosaurids evolved from medium-sized predators to the apex predators of the Late Cretaceous, and suggests that this evolution may have been accelerated by ecosystem-wide changes, such as the extinction of other large predators.
Reconstruction of Behavior and Ecosystems
First Direct Evidence of Multi-Species Herds
2025-08-12
Fossil footprints of a mixed herd of ceratopsians and ankylosaurs have been discovered in Dinosaur Provincial Park, Canada.
"Why do different species herd together?"
The most logical inference is that "species with different sensory and defensive mechanisms could increase the overall survival rate of the herd by cooperating. Like modern herbivores, different species cooperate to protect themselves from predators." This is considered evidence that ceratopsians and ankylosaurs engaged in complex social behavior. The discovery of tyrannosaurid footprints nearby strongly supports this hypothesis.
Reconsidering Evolutionary Paradigms
Dinosaur Origins in Hot, Arid, Low-Latitude Gondwana
2025-07-18
A research team from University College London (UCL) has proposed a new model that accounts for sampling bias in the fossil record, suggesting that early dinosaurs evolved in hot, arid, low-latitude Gondwana, rather than the previously thought cold, high-latitude regions. This theory suggests that dinosaurs were originally heat-tolerant and later acquired endothermy, allowing them to expand into colder regions.
Was Pre-Extinction Diversity Decline Just an "Illusion"?
2025-04-10
Researchers at University College London (UCL) have published findings suggesting that "the decline in dinosaur diversity at the end of the Cretaceous was not a biological decline, but rather a bias in the fossil record (sampling bias) caused by geological fluctuations." This suggests that if the asteroid had not struck, dinosaurs might have continued to thrive, adding a new perspective to a long-standing debate.
- Fossil Discovery Rates and Dinosaur Populations
The conventional fossil record indicated that the number of dinosaur species peaked around 75 million years ago and then declined over the 9 million years leading up to the asteroid impact. However, the research team concluded that "this decrease in fossils was caused by a reduction in the exposure of fossil-bearing rocks from the era before the asteroid impact." In other words, the fossil record itself was incomplete. - New Analytical Methods
The team used fossil data from North America and employed a technique called "occupancy modeling." They estimated the potential range where dinosaurs actually lived (occupancy rate) based on geographical, geological, and climatic factors.
The results showed that the ranges of four major dinosaur groups (Ankylosauridae, Ceratopsidae, Hadrosauridae, and Tyrannosauridae) were stable for the last 18 million years leading up to the asteroid impact.
This study suggests that dinosaurs were not on a path to extinction at the time of the asteroid impact but were still maintaining their prosperity.