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Kasia

A "dog-sized" marsupial lion fossil found in Australia

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Max-fossils

Great article! Thanks for posting.

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Tidgy's Dad

I agree, a very interesting read. :)

Thank you! 

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KimTexan

How do they determine it is a marsupial from just a skull, teeth and a humerus?

 

Are there characteristics in just these few parts of the skeleton or do they just assume they were marsupial based on location? 

 

I know the monotremes, like the platapus have structural differences in their jaws structure and other parts that can help distinguish them from other mammalian groups, but I don’t know about marsupials. 

Surely they don’t base it on location, because Australia does have native mammalian species. I’m just curious.

 

Maybe @Ash or @Jesuslover340 can enlighten me. Do you know what skeletal differences marsupials have that can enable identification as a marsupial from just a skull, teeth and humerus? 

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Foozil
1 hour ago, KimTexan said:

How do they determine it is a marsupial from just a skull, teeth and a humerus?

 

Are there characteristics in just these few parts of the skeleton or do they just assume they were marsupial based on location? 

 

I know the monotremes, like the platapus have structural differences in their jaws structure and other parts that can help distinguish them from other mammalian groups, but I don’t know about marsupials. 

Surely they don’t base it on location, because Australia does have native mammalian species. I’m just curious.

 

Maybe @Ash or @Jesuslover340 can enlighten me. Do you know what skeletal differences marsupials have that can enable identification as a marsupial from just a skull, teeth and humerus? 

The teeth of marsupials are easy to tell apart from other groups of mammals to the trained eye. And believe it or not, thylacoleo and related species have teeth surprisingly similar to macropods. Also things like the large forward-facing incisors, which are a characteristic of diprotodontidae.

I'm sure there are many other reasons that Ash or Jesuslover340 can explain :) 

 

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Jesuslover340
19 hours ago, KimTexan said:

How do they determine it is a marsupial from just a skull, teeth and a humerus?

 

Are there characteristics in just these few parts of the skeleton or do they just assume they were marsupial based on location? 

 

I know the monotremes, like the platapus have structural differences in their jaws structure and other parts that can help distinguish them from other mammalian groups, but I don’t know about marsupials. 

Surely they don’t base it on location, because Australia does have native mammalian species. I’m just curious.

 

Maybe @Ash or @Jesuslover340 can enlighten me. Do you know what skeletal differences marsupials have that can enable identification as a marsupial from just a skull, teeth and humerus? 

Well, your marsupials are considered to have a more 'primitive' dentition. Marsupials are grouped into two groups accordingly-polyprotodonts (possums and bandicoots) and diprotodonts (wombats and diprotodon). Polyprotodonts have four or more upper incisor teeth; diprotodonts have two (placentals also typically have four, but the following should define further differences). Furthermore, marsupials tend to have three premolars and four molars (many also have reduced canines), whereas placentals have the opposite: four premolars and three molars lining the maxilla and dentary. Placentals also have second generation dentition; placentals only replace a few select teeth. There's specific dentition differences between your macropods and again between your diprotodontids such as Diprotodon, Eowenia, Zygomaturus, etc., but the above should adequately explain the dentition differences between placentals and marsupials, at least :)

 

So in answer, yes, you can determine between marsupials and placentals given the skull and dentition, at least. Mammal dentition is diagnostic- usually to a species level- as a general rule of thumb. Humeri...not so much unless it is associated with an identifiable dentition, though they can indicate the common movement of an animal (and by extension, its lifestyle). Hope this helps :)

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Ash

What she said :P ^

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