However, the real surprise came when researchers realized that alnashetri There was no highly specialized, late-stage alvarezsauroid. Instead, despite living in the Late Cretaceous, it occupied an early-branching position among the earlier, basal members of the clade.
This combination of small size and early-branching conditions fundamentally breaks our previous models of how these animals evolved. If the miniaturization of alvarezsauroids was strictly linked to their lifestyle as stubby-armed insect-eaters, an early-split species alnashetri There should be some transitional features on a steady, clade-wide march toward that extreme endpoint. But it didn’t seem like that.
“It’s a very long-limbed animal, so it was probably quite fast. My best analogy would be like a roadrunner of the American West,” Makowiecki said.
hands and teeth
Late alvarezsaurids had short, strong forelimbs that were less than half the length of their thighs. alnashetriHowever, its forelimbs were comparatively long, accounting for 61 percent of the length of its entire hind limb. Although it had three-fingered hands with strong first digits, a hallmark of its group, it retained slender second and third digits, unlike its later counterparts.
Other features that challenge established evolutionary models of miniature dinosaurs alnashetriThe jaws and teeth. Its teeth consisted of non-serrated teeth set in sockets, but importantly, these teeth were not very small, as they were in late alvarezsaurids. Shuvuiya Or jaculinicus. “This separated the evolution of smaller body size from physiological specialization,” Makowiecki explained.
The team concluded that extreme miniaturization in alvarezsaurids did not necessarily co-evolve with the development of smaller weapons more suitable for digging or smaller teeth designed for crushing ants and/or termites. Instead of a broad trend where the entire lineage continually shrank over time, a new evolutionary model involves alnashetri This suggests that alvarezsaurid body mass fluctuated frequently. alnashetriIt turns out, it acquired its 700-gram frame independently from other, highly specialized alvarezsaurid species.
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