High school biology
- Taxonomy and the tree of life
- Biodiversity and natural selection
- Genetic variation, gene flow, and new species
- Discovering the tree of life
- Phylogenetic trees
- Understanding and building phylogenetic trees
- How do we know which kinds of dinosaurs were most closely related?
- Phylogeny review
How do we know which kinds of dinosaurs were most closely related?
Understanding questions of dinosaur behavior and biology depends on a firm understanding of their evolutionary relationships. To reconstruct the evolutionary relationships between different groups of dinosaurs, one must carefully study and analyze the anatomy, essentially searching for characteristics that are shared among different kinds of dinosaurs. These characteristics are then interpreted to have been present in the common ancestor and inherited by its descendants. This analysis produces a branching diagram, called a cladogram, on which different kinds of dinosaurs are shown at the endpoints of the branches. Created by American Museum of Natural History.
Want to join the conversation?
- Do cladograms ever change (for instance when we develop new techniques or insights and become able to analyse more characteristics)?(9 votes)
- I've read about debates in the cladistic world about, for example, whether DNA evidence (for modern animals) should inform the cladograms, or if cladograms should be based entirely on physical characteristics (with DNA analysis left as a completely separate line of evidence). The diagrams change with the data as well, for example recently a species of ceratopsian was found to likely be the final adult stage of the Triceratops, so that dropped a whole species off the list. Phenomenon like sexual dimorphism (where males and females of the same species look different) and convergent evolution (where distantly related animals develop the same adaptation under similar environments) provide challenges to cladistics that get revised with new data or new interpretations of existing fossils.(12 votes)
- how do you know a dinosaur is carnivorous or omnivorous looking at the first time at their fossils?(4 votes)
- I believe paleontologists look first to see whether the fossil in questions has any teeth. If it does, then this is a big help in determining the foods a dinosaur ate. In general, a meat-eating dinosaur will have long, serrated teeth like steak knives, or small but sharper teeth. Basically, the canines and other teeth used for cutting are more prominent. In omnivores, the canines and back teeth (molars) will both show wear, as both are being used. Plant-eaters would have less canines and more molars; several hadrosaurs had hundreds of molars in the backs of their mouths, to better grind of the tons of plant matter they ate every day (I think most of a brachiosaur's life was spent eating).
If there are no teeth available, I believe paleontologists look for other signs, like rocks in the stomach, usually found in plant-eaters (these stones help to grind up plant material) , or other things in the stomach, like that dinosaur's last meal. Claws, teeth, girth size, and other such characteristics can help determine whether a dinosaur was a carnivore/herbivore.(11 votes)
- how did the trex got the name ?(2 votes)
- Tyrannosaurus means 'Tyrant Lizard', in probably in reference to it's gigantic size and role of apex predator(6 votes)
- how do I be came a paegtallagist.(2 votes)
- My man's really spelt 'palaeontologist' and 'paegtallagist' 5 years ago.(1 vote)
- how did they say T-Rex is ferocious?(2 votes)
- Or "terrifying?" They believe they base it solely on if it was a large predator.(2 votes)
- Is it possible to do what John Hammond did in Jurassic park?(3 votes)
- I don't think it would be possible to recreate Dinosaurs, because we may not get the correct DNA for cloning.
But if researchers did find a perfectly preserved mosquito with a body full of dinosaur blood, retrieving its DNA would still be difficult. The blood with the dinosaur DNA would be surrounded by the body of an insect, which has its own DNA. There could also be DNA from other cells trapped in the amber, which could contaminate the sample. Then, of course, there's the DNA in the laboratory itself -- and in the body of the scientist doing the extraction.
The fictional scientists in "Jurassic Park" try to get around these difficulties by combining dinosaur DNA with frog DNA. But this would be like trying to assemble a jigsaw puzzle using billions of pieces that come from two different puzzles. Plus, frogs might not be the best candidates for providing replacement DNA. Today, one of the most prevalent theories about the fate of the dinosaurs is that some evolved into birds, not frogs.
On top of all that, the most common form of cloning used on animals today involves nuclear transfer. Scientists put the nucleus of one cell into a second cell of the same species after destroying the second cell's nucleus. There are no dinosaur cells or dinosaur eggs that could host new set of DNA. Researchers would have to find a different way to let the DNA grow into a living dinosaur.(1 vote)
- can we clone a dinosaurs(1 vote)
What's shown in Jurassic Park is largely impossible, even if we did have Dinosaur blood. However, some scientists have theorized that 'reverse engineering' birds (modern Dinosaurs) could lead to Dromeosaur ( "raptor" ) like animals living again(3 votes)
- how did the dinosoars die(3 votes)
- A massive asteroid (a big chunk of rock and/or metal from space) hit the Earth, throwing tons of dirt into the air, blocking out the sun for years. In addition, the asteroids triggered an enormous amount of volcanic activity, further poisoning the atmosphere and darkening the skies even further(3 votes)
- how do we know what dinosaurs looked like with just bones?(1 vote)
- are we related to dinosaurs in any way(0 votes)
For us to understand the genealogy, the relationships, among dinosaurs we use the same techniques and tools as other biologists use to understand how different groups of organisms are related. The primary one that we use is a technique called cladistics, and what cladistics is, is that we just look at number of attributes in the animal and then we try to find the shortest path through those attributes. When I say shortest path I mean the least evolutionary steps. I mean, for instance if we had, you know, three animals in the room with us now, and we had, say we had a human, say we had a mouse, and say we had a lizard. Well one of the attributes that links the mouse and the human together is hair, so if you would say that the mouse and the lizard were most closely related, you would have to have two evolutionary steps, the independent origin of hair. But by saying that hair only originated once, it's evidence for a preferential relationship between humans and mouse. So that's a very simple example, but we do that with hundreds of characters and hundreds of animals sometimes and then we have computer algorithms, which actually go through the matrix and find the shortest path through it, and it results in a family tree of these animals.