What Aspidites really are...

[PatrickT]

I get my Woma python in the next days and would like to debate a bit about the cladisitic of their genus Aspidites.

Only two species are in this genus: the Woma and the blackheaded python. Both are living only in australia and have many unique characteristics. They lack heatpits and their entire body looks different to any other python species. Infact genetic analysis shows that they are not really related to the python genera, they are just put there because they don´t fit anywhere else.

So what are they? It is very possible that they belong to an ancient genus called Madtsoniidae. Some of the most famous snake fossils like Sanajeh belong to this genus. It was once spread over the entire globe. Fossils are known from the middle creatacious. They went extinct in most parts of the world roughly 50 million years ago but did hold out in Australia. The last known extinct of this genus was the Wonambi species, which the Aboriginies still know.

No further studies were done regarding this but it is very possible that the Woma and Blackheaded python both belong to the Madtsoniidae. That would mean they are not just not pythons but not even in the super order Boidae at all.

http://www.amazingamazon.com.au/media/catalog/product/cache/1/thumbnail/9df78eab33525d08d6e5fb8d27136e95/w/o/woma_python.jpg

[eminart]

Very interesting. I did not know this. I do know that both species are beautiful snakes that are on my "I'd like to have one list".

[Derek Roddy]

Actually both Womas and BHPs do have a heat pit under their rostral scale.Many of us who have kept Womas and BHPs for years already knew this as they are VERY receptive to temp changes. It was proven several years ago by biologist in Australia when tissue sampling was done on both species.

I will also say that there has been a "small scientific movement" to move the Woma and BHPs out of the python genius all together because of the differences in their genetic code, behavior, etc.

They're a great species and nothing else like em. If anything, the closet I've personally kept has been an indigo snake....without the stinky mess. haha.

D

[PatrickT]

Actually both Womas and BHPs do have a heat pit under their rostral scale.Many of us who have kept Womas and BHPs for years already knew this as they are VERY receptive to temp changes. It was proven several years ago by biologist in Australia when tissue sampling was done on both species.

I will also say that there has been a "small scientific movement" to move the Woma and BHPs out of the python genius all together because of the differences in their genetic code, behavior, etc.

They're a great species and nothing else like em. If anything, the closet I've personally kept has been an indigo snake....without the stinky mess. haha.

D


What the two Aspidites species have can´t be really called a "heat pit" in the classical stance. Its like some primordial form of it and consists from temperature sensitive tissue under the rostral scale as you said yourself. Its morphological completly different to the ehat pits we know from Boas, pythons and vipers.

Aspidites are an incredible amazing group of snakes and it would be amazing if more research could be done to bring some light in their relationship with other species. Its obvious they aren´t pythons in any way.

[RAD House]

This is very interesting. Is it a primordial form or just an example of convergent evolution? By saying it is primordial you are implying that the ancestors of both groups had a system similar to the Aspidites, but this evolved into something more complex in Boidea. If the two organs are in fact so different I would more likely think it is an example of convergent evolution, which more supports your idea of being two separate families. Proving them to be part of an extinct family may be rather difficult unless you have preserved DNA or full skeletal remains from species with in said family.

[PatrickT]

This is very interesting. Is it a primordial form or just an example of convergent evolution? By saying it is primordial you are implying that the ancestors of both groups had a system similar to the Aspidites, but this evolved into something more complex in Boidea. If the two organs are in fact so different I would more likely think it is an example of convergent evolution, which more supports your idea of being two separate families. Proving them to be part of an extinct family may be rather difficult unless you have preserved DNA or full skeletal remains from species with in said family.

Its hard to say. Aspidites definitly have heat "sensor" under their rostral. But its completly different to the heat pits we know from pythons. It could be the primordiwl form of those pits or simply convergent evolution. The problem is that most snake fossils are very fragmented. So it would be hard to prove. All we know so far is that they are not really Pythons at all from an genetic point of view.

[RAD House]

I was never that interested in BHPs or womas, but I am a sucker for living fossils and Lazarus taxon. Hmm I might need to add these guys to the list.

[Albert Clark]

Thanks to all of you, Patrick, Derek and Meso for sharing all of that information. I definitely had no clue about this.......

[Derek Roddy]

What the two Aspidites species have can´t be really called a "heat pit" in the classical stance.

Actually, that's exactly what it is. It's exactly the same as any other python or boa species. It's very apparent when you hold one and see in person. But, from a bio level, they are exactly the same.

Cheers,
D

[Derek Roddy]

Here's an example
http://img.photobucket.com/albums/v321/derekroddy/derekroddy024/186354520.jpg (http://smg.photobucket.com/user/derekroddy/media/derekroddy024/186354520.jpg.html)

D

[shaunyboy]

interesting thread folks




cheers shaun

[MDT]

Not sure if this adds anything, it's an older study...but I saw this about a week ago...Python phylogenetics: inference from morphology and mitochondrial DNA - RAWLINGS - 2008 - Biological Journal of the Linnean Society - Wiley Online Library (http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2007.00904.x/abstract)

Kinda gives some info on the research...mitochondrial DNA analysis..
I give this thread about 1 page before Hoser jumps in and calls us trolls and tells us how stupid we are.


And, to echo Shaun..This is an interesting thread.

[SoPhilly]

Interesting... so this study is saying that the rostral heat pit was maybe a reversal back to a more primitive form (than the typical heat pits we usually think of) that may have happened as they started burrowing. So - to keep dirt out better, they hid them under their little shovel noses(lol:D)? Am I reading this right?

Also, can some one more biology conversant explain what "the genus Aspidites is embedded among the Australo-Papuan genera." means? Not sure what the use of "embedded" signifies in this context.

[MDT]

that was kinda my take as well. however....i didn't pay for the whole paper. just reading form the abstract.

[prairiepanda]

My school library has access to that paper. It's pretty long, so I didn't go into great depth reading it, but according to the genetic evidence Aspidites most likely evolved after Python and branched from species with "normal" heat pits. So yes, the rostral heat pit is a result of convergent evolution and not a remnant from their more primitive ancestors.

[MDT]

My school library has access to that paper. It's pretty long, so I didn't go into great depth reading it, but according to the genetic evidence Aspidites most likely evolved after Python and branched from species with "normal" heat pits. So yes, the rostral heat pit is a result of convergent evolution and not a remnant from their more primitive ancestors.

Thanks for looking into that :)

Pretty cool

[SoPhilly]

Awesome. I love this forum.

[Derek Roddy]

Here is a copy of the original paper about the rostral pit.

A New Type of Infrared Sensitive Organ in the Python Aspidites sp.
by Guido Westhoff Shaun P. Collin
Pythons are well known to possess an infrared sense enabling them to perceive infrared radiation. It is believed that the infrared sense is mainly used to localise their warm blooded prey. The infrared sensitive organs are comprised of infrared sensitive thermoreceptors, which are embedded within specialised pits of the labial scales. Infrared signals are detected by these pits lined with thermoreceptors, which project to the cns via the trigeminal nerve and a specialised nucleus within the hindbrain (nucleus of the lateral descending trigeminal tract: nLTTD) to be relayed towards the midbrain and forebrain. The nLTTD is only found in infrared sensitive snakes. Aspidites sp. are the only members of the Pythoninae that do not possess labial pits. The lack of labial pits and thus the obvious lack of the infrared sense in Aspidites have been interpreted in the past either as a primitive character of this genus or as a secondarily loss due to the fact that these pythons feed on-cold blooded prey. We investigated a conspicuous U-shaped single pit located in the rostralia of Aspidites sp. which points downward in a resting specimen but clearly faces forward if the python raises its head. The rostral position and the overall shape of the pit allow frontal object localisation to be mediated by shadowing, where certain regions of the pit are differentially stimulated with regard to the position of objects in front of the animal. Scanning electron microscopy (SEM) has confirmed that the ultrastructure of the fundus of the pit resembles the fundus of labial pits in other pythons i.e. it possesses enlarged shingle like cells with micropits. Transmission electron microscopy (TEM) also reveals the presence of typical infrared thermoreceptors within the pit that are not found in other scales. Furthermore, the brain of Aspidites melanocephalus reveals a structure that can be regarded as a nLTTD. We propose that Aspidites clearly possesses an infrared sense and the unusual position of the single, downwardly-directed pit in the rostralia has evolved in response to its fossorial lifestyle i.e. to avoid damage to the pit from soil and debris. This arrangement is clearly different to the open labial pits of other pythons, which are directed laterally from the head. This work was partly supported by the Feodor-Lynen program of the Alexander von Humboldt Foundation.
Type: oral contribution
Theme: reptiles, snakes, morphology
Entity: Westhoff: Institute of Zoology University of Bonn Poppelsdorfer Schloss 53115 Bonn, GERMANY e-mail: gwesthof@uni-bonn.de Collin: Room A205 Ritchie Research Laboratories School of Biomedical Sciences The University of Queensland Brisbane, Queensland 4072 Australia e-mail: s.collin@uq.edu.au"

Cheers,
D

[Derek Roddy]

This is also a cool video (with Dave from Pilbara Pythons) showing a nice WA BHP in which he shows and talks about the pit study. Dave sorta spear headed the whole project.
https://www.youtube.com/watch?v=EAbIzjFEjRo

Cheers,
D

[PatrickT]

Anyways i cant wait to get mine in a few days. :D