We’re rewarding the question askers & reputations are being recalculated! Read more.
48

Birds are both flying dinosaurs and flying reptiles. Yes, that's potentially confusing. To understand the apparent contradiction, you have to understand how modern classification of organisms works (phylogenetic systematics). Under the old (Linnean) classification system, Reptilia (reptiles) was an order and Aves (birds) was a separate order. Phylogenetic ...


24

In addition to kmm's excellent answer, I'd like to present the xkcd point of view. By any reasonable definition, T. Rex is more closely related to sparrows than to Stegosaurus. Separation by time Phylogenetic distance Physical similarity Birds aren't descended from dinosaurs, they are dinosaurs. Which means the fastest animal ...


23

There are lots of papers on this. A good summary article is Why sauropods had long necks; and why giraffes have short necks, by Taylor​ and Wedel. They list a number of anatomical features that allowed sauropods to support such long necks: Several anatomical features enabled this extreme elongation, including: absolutely large body size and quadrupedal ...


22

Things in the paper that strike me as suspicious Associating toxic plant defenses with the Cretaceous Although there continues to be uncertainty about precisely when plants first evolved toxic defenses, this period of angiosperm proliferation would seem to be a strong candidate case. (pg 50) Against this Gleadow and Moller (2014) discuss Cyanogenic ...


20

Rather than talk to the specifics of this idea, which others have already done well, I'll contextualise it as one anti-consensus view among many. Many. Many. The extinction of non-avian dinosaurs is the most publicly well-known part of a much larger systemic event at that time, one of the largest extinction events in the last 500 million years. The ...


15

No, it's not convincing; angiosperms evolved in the middle part of the dinosaurs' reign, not the end, and toxins evolve slowly which gives herbivores a chance to compensate, also conifers can be riddled with toxins just as easily. Lastly, the idea that dinosaurs could not learn taste aversion is ludicrous; it is one of the simplest neurological feats, ...


13

Yes, there are many early examples of ceratopsians before Triceratops. The oldest clear member of the lineage is Liaoceratops: "the oldest ceratopsian ever found ... was about the size of a large dog. It had a blunt beak and a dainty neck frill. ... Liaoceratops was a puny forebear of the feisty Triceratops. Size, horns and spectacular frills came later in ...


8

I'm not an expert, but I think that you have to be specific about the flying animals to which you are referring. Pterosaurs are not classed as dinosaurs, whereas modern birds are descended from theropod dinosaurs which is where feathers appeared.


7

Asides from flight-capable modern birds and their early ancestors1, there are several other therapod dinosaurs which palaeontologists suspect were capable of flight, "but in a manner substantially different from that of modern birds": Dromaeosaurids Microraptor Scapular orientation in theropods and basal birds, and the origin of flapping flight, Acta ...


7

I'm pretty sure that's an Achelousaurus. Two curved horns on top, plus hump on nose: Front view: Side view: (for nose)


6

Do birds descend from dinosaurs? First, it is confusing to say things like Birds descend from dinosaurs Humans descend from monkeys Mammals descend from vertebrates Snakes descend from animals It is much more correct to say Birds are dinosaurs Humans are monkeys Mammals are vertebrates Snakes are animals You should definitely have a look at the post If ...


6

Source of information See the post The best free and most up to date phylogenetic tree on the internet? for info about how to find such information. Generally speaking, you might be interested in an intro to phylogenetics such as the one provided in this answer for example. Where are dinosaurs in the tree of life? Dinosaurs fall within the Reptiliomorpha ...


6

I suppose that by the mass extinction, you are referring to the Cretaceous–Paleogene extinction event that happened 66 mya. The Most Recent Common Ancestor (MRCA) of all birds lived about 113.3 mya (early Cretaceous, according to this in oneZoom.org). So yes, the MRCA of all birds is definitely older than the Cretaceous–Paleogene extinction event. As you ...


6

There are two questions here. Dinosaurs were larger because their basic anatomy is better at being large than mammals. Their spine is better braced (no lumbar region), their breathing mechanism scales better, and their hip structure is stronger. This is called a preadaptation, or when an organism or group of organisms just starts with a head start on a ...


5

Basic misunderstand about how one can make sense of nature Nature is not a conscient being (or at least not falsifiable conscient being) trying to optimize the amount of flora or whatever you would like to optimize. There is no conscious will in the processes of evolution, in the course of a meteorite or in the decay rate of some radioactive material. ...


5

Note nowhere in the article does it mention the rear wings flapping. The rear wings do not provide lift, they are acting as control surfaces to improve stability and maneuverability. (think of the tail of a plane).earlier/proto flies have far more demand for control surfaces than developed/derived fliers due to lacking more precise control of flight surfaces....


4

Wikipedia has a nice summary: https://en.wikipedia.org/wiki/Category:Cretaceous_dinosaurs


4

There has been a long debate whether dinosaurs were ectotherms or endotherms but most of the recent studies (hypotheses)1 show that they were endotherms. In one of the most promising recent studies (in 2011), a technique called clumped-isotope thermometry2 (which is based on a reaction involving the bond between carbon and oxygen; and used in paleoclimate ...


4

Radically different body shapes and sizes represent overall phenotype. Overall phenotype was used briefly in the 1960s and 1970s for species identification under a statistical distance method called "phenetics". However, phenetics has been rejected as a valid method of species identification. Similarly, although ecologists widely use the Biological Species ...


4

There is a good attempt at a simulation of 4 winged flight of Microraptor on BBC's Planet Dinosaur. There's another Planet Dinosaur video about their venomous teeth and hunting tactics. And a Microraptor locomotion video on Attenborough's Conquest of the Skies (Sky 3D).


4

Unlike mammals, saurischian dinosaurs don't have to chew their food. Like birds they have a gizzard to do that instead. Look at a modern ostriches: they have a very small head because the head is only used to gather food not process it. Mammals process food in the head (chewing) so the head has to be large to support the muscles, teeth, and other apparatus ...


4

They are called Nutrient Foramen which are innervation of blood vessels and nerves, you see the same thing in reptile and bird skulls (mammals tent to pack it all into one or two large openings). They feed blood vessels and nerves to the gums, lips, and face. Dinosaurs do seem to have more of them, but size making them more noticable is also a factor. The ...


3

Most of the dinosaur predators were derived from a common ancestor. The body plan was efficient, and the theropod predators speciated widely (including birds). But statistically, the number of therapod predators are not independent observations, but linked to each other through ancestry. Similarly, most mammalian predators (Carnivora) are linked to a common ...


3

This is actually a really good question. Several large groups of dinosaurs (theropods, most famously) were bipedal, and highly successful at it; while today, very few mammals are bipedal. What was it about dinosaurs that made bipedalism a successful solution, while mammals typically prefer quadrupedalism? There were two important differences between the ...


3

tl;dr There is no mistake if there is no intention pre-historic is not the term your were looking for Some animals were big during the "dinosaur era" but not all and the largest animal to ever exist is extant today Ancient dinosaurs have been around for 170 millions years. That's a very long time, much longer than anything you seem to be comparing to Most ...


3

There was a taxonomic revolution brought about by cladistics https://en.wikipedia.org/wiki/Cladistics. Willi Hennig wrote about it in 1950, but he was an East German, and his work did not gain traction in the West until it was translated into English in the late 1960s. Then it took a while to become consensus. Since then, all taxonomy is based on ...


2

Dinosaur biostratigraphy makes it not possible to answer your question through all of history. 8Ma is the highest longevity species I found in a biostratigraphy table. Dinosaurs are faster evolving than crocodilians who have 1/3rd as big a genome as a mouse and 1/6th that of a shark. Adaptive genus existed for 5-30 million years, and well known clades exist ...


2

Is it possible that nearly human mammals existed before the last mass extinction dinosaurs? Short answer No! Longer answer The ancestor of all mammals lived about ~180 millions years ago (see here), so much before the Cretaceous–Paleogene extinction event (~65 millions years ago). The ancestor of all primates lived ~65 millions years ago (see here), so ...


2

From the wikipedia page on Apatosaurus: Most size estimates are based on specimen CM 3018, the type specimen of A. louisae. In 1936 this was measured to be 21.8 m (72 ft), by measuring the vertebral column.[5] Current estimates are similar, finding that the individual was 21–22.8 m (69–75 ft) long and had a mass of 16.4–22.4 t (16.1–22.0 long ...


Only top voted, non community-wiki answers of a minimum length are eligible