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Per the comments, the actual paper seems pretty like a pretty straightforward operation of normal science: Somebody noticed something that looked off about one of the bones and decided they'd look into it more carefully. They found that yes, that bone appears to have been an accidental inclusion, and in fact the rest of the skeleton makes more sense without ...


4

I've not read it but this SE question Why don't mammals have more than 4 limbs? though not a duplicate (it asks about mammals not all vertebrates) may have some elements in its answers pertinent to your question. And the question Why are there no vertebrates with more than four limbs? has been asked in Quora where it has 7 answers you may find useful. ...


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From Raup (1986). Up to 4 billion species of plants and animals are estimated to have lived at some tlme m the geologic past (2), most of these in the last 600 million years (Phanerozoic time). Yet there are only a few million species living today. Thus, extinction of species has been almost as common as origination. I am not sure how exactly has ...


3

There are several defining morphological characteristics of dinosaurs. Including their ankle structure and perforated acetabulum, Aka the hole in their hip goes all the way through, as well as a few other minor features. These combined makes it literally impossibly for a dinosaur to take on a sprawling pose without breaking hind leg in many places, this is ...


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Short answer Mammalian hearing is unique and amazing. The mammalian ear is unique and highly sensitive with a built in amplification system that means even minute changes in sound can be detected. The bony amplification is also the reason the mammalian (or at least therian) cochlea is huge, every incremental increase yielded markedly more information, it ...


2

It's fairly common. It is believed to have evolved two times independently, basically in both groups presumed to use their tails as weapons. Both Diplodocoidea and Euhelopodidae have species with forked chevrons and evolved it independently. It is fairly diagnostic since it is not seen outside these groups. Source Independent half chevrons (two rows of ...


1

late Maastrichtian is probably it. Part of the problem you are running into is the Triceratops genus is in flux, there is debate about whether certain species belong in the genus. Such as whether triceratops and torosaurus are the same species. The other problem you are running in to is the accuracy of dating methods, many fossils are dated indirectly, ...


1

I think you are confused about what erect limbs means, monotremes have erect hindlimbs. Erect is not the same as pillar erect (which is exceedingly rare) Just because a limb is bent or a joint can rotate does not mean it is not an erect limb. More importantly terms like semi-erect don't actually mean much, it is a weak gradation not discrete categories. ...


1

How biologist discover "DNA" informations from dead and oldest fossils such as dinosaur. They don't. In general fossils contain very little organic material. It's all been replaced by stone (silicates). On top of that DNA degrades over time. There have been a handful of cases where researchers have claimed to recover small fragments of DNA from dinosaur ...


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I am proud that I can answer your very, very good question! You are right that the soft tissue of ammonites is very, very rare. But along with beaks (I believe you meant aptychi) you can find something with similar function called radula, which is (at least for devonian ammonoids) both in morphology and in number of elements identical to recent coleoids! ...


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