Marine reptiles of Madagascar

[pachy-pleuro-whatnot-odon]

Hi all,
 

I recently became aware that Madagascar appears to have a fully developed and interesting Mesozoic marine reptile record, yet am not particularly able to find any information on them. The only article I have come across is Bardet and Termier, 1990, "Première description de restes de Plésiosaure provenant de Madagascar (gisement de Berere, Campanien)". However, I've been unable to track this article down. As such, I was wondering whether anybody on TFF might have any information on them.

 

Basically, I'm starting from scratch, so would be very interested in the clades of marine reptile that are known from the region, if not recognized genera or even species. What formations have remains been found in, to what stages in earth geological history do these date, and where geographically are these located? Ideally, there'd be some open-access articles I could refer to, yet any bit of information is welcome.

 

Thanks in advance!

[IsaacTheFossilMan]

Hmm, weird, I can't seem to find any either! 

[pachy-pleuro-whatnot-odon]

  

3 hours ago, IsaacTheFossilMan said:

Hmm, weird, I can't seem to find any either! 

Which to me seems strange. Because when you check PaleoBioDB, for instance, there are plenty of records of marine deposits dating to the Jurassic (primarily Late, by the looks of it), the entire Cretaceous period, and even some Early Triassic...

[IsaacTheFossilMan]

5 minutes ago, pachy-pleuro-whatnot-odon said:

  

Which to me seems strange. Because when you check PaleoBioDB, for instance, there are plenty of records of marine deposits dating to the Jurassic (primarily Late, by the looks of it), the entire Cretaceous period, and even some Early Triassic...

Yeah, it is strange. When I finish my work, I will have a deeper look for you!

[IsaacTheFossilMan]

These are ones I have found already, as I said before, I will look further later:

 

Download to a PDF - unsure if it'll be of use

This mentions 'hovasaurus' - a Madagascan marine reptile

This one will be very useful

 

 

[pachy-pleuro-whatnot-odon]

Cool, thanks for the articles! Will take a closer look at them as soon as I get some time behind a computer. How did you manage to find these so quickly? Then again, I myself have been looking more for information on later Mesozoic marine reptiles up till now, from the Jurassic and Cretaceous...

[PFOOLEY]

@pachy-pleuro-whatnot-odon, Madagascar is said to have been part of Gondwana...adding this as well as Gondwanan Continents to your search may yield more fruitful results.

[pachy-pleuro-whatnot-odon]

On 2/19/2021 at 5:50 PM, PFOOLEY said:

@pachy-pleuro-whatnot-odon, Madagascar is said to have been part of Gondwana...adding this as well as Gondwanan Continents to your search may yield more fruitful results.

Thanks for the suggestion! Unfortunately, including "Gondwana" in the search criteria (in addition to things like "plesiosaur" or "ichthyosaur") only resulted in the one following match: Carroll (1981), "Plesiosaur Ancestors from the Upper Permian of Madagascar".

[IsaacTheFossilMan]

On 2/19/2021 at 1:47 PM, pachy-pleuro-whatnot-odon said:

Cool, thanks for the articles! Will take a closer look at them as soon as I get some time behind a computer. How did you manage to find these so quickly? Then again, I myself have been looking more for information on later Mesozoic marine reptiles up till now, from the Jurassic and Cretaceous...

Sorry for the late reply, I only just saw this. Lots of googling for many different things, my friend! I always google using different wording, and word order, and googling for "famous" creatures from that time usually dredges up articles using that for a title!

[pachy-pleuro-whatnot-odon]

18 hours ago, IsaacTheFossilMan said:

Sorry for the late reply, I only just saw this. Lots of googling for many different things, my friend! I always google using different wording, and word order, and googling for "famous" creatures from that time usually dredges up articles using that for a title!

No worries, I expect this question may take some time answering. Anyway, I thought I had already checked all the obvious criteria. But may be I need to dig a bit deeper. Problem with deeper, however, is that it's increasingly based on prior knowledge, if not assumptions...

 

I found this interesting quote in Dal Sasso et al. (2016), however (itself, though not pertaining to a marine reptile, an article that may be of interest to others for its description of mesoeucrocodylian Razanandrongobe sakalavae):

Quote

The Middle Jurassic (Bathonian) deposits of the Mahajanga Basin yield a peculiar and poorly known fossil vertebrate fauna. Teeth of thalattosuchian crocodilyforms, plesiosaurs, and possibly ichthyosaurs, as well as dinosaurian remains (mainly sauropods) have been reported over the last century (Thevenin, 1907; Besairie, 1936; Besairie, 1972; Lavocat, 1955; Ogier, 1975; Bonaparte, 1986).

 

The references included above are the following:

• Besairie, 1936. Recherches géologiques à Madagascar, première suite. La géologie du Nord-Ouest.
• Besairie, 1972. Géologie de Madagascar I. Les Terrains Sédimentaires.
• Bonaparte, 1986. Faunal change across the Triassic-Jurassic boundary.
• Lavocat, 1955. Étude des gisements de dinosauriens de la région de Majunga (Madagascar).
• Ogier, 1975. Étude de nouveaux ossements de Bothriospondylus (Sauropode) d'un gisement du Bathonien de Madagascar.

As with the earlier mentioned Bardet and Termier (1990), it seems most of these articles were published too long ago to be available online. So, I thought I'd have a look on Google, Archive.org and the Gutenberg Project to see if they might have any of the above literature. But, unfortunately, I wasn't able to find any of it. I did come across a three-piece monograph on the geology of Madagascar, in French and dating to 1922-1923 (part 1, 2 and 3), of which part 3 has a geological map (p. 468). With each volume comprising multiple hundreds of pages, I haven't searched through them yet to look for fossils - let alone those of marine reptiles - yet.

 

One interesting find I made - but, again, not pertaining to marine reptiles - is Thevenin (1907), "Paléontologie de Madagascar: IV. - Dinosauriens". Although it seems to mainly refer to terrestrial species and actual dinosaurs, it might still be worth glancing over in search of references to marine reptiles...

 

I've also found these two publications:

• Andrianandrasana, 2006. Essai de caracterisation paleontologique de la Formation de Berivotra, Mahajanga, Madagascar.
  This describes the stratigraphy of the Berivotra Formation in Mahajanga/Majunga in Madagascar, including some of its fossiliferous inclusions (no marine reptiles, though).
• Ramaniraka, 2017. Appui du sig a la determination des sites a dinosaures entre les baies de Bombetoka et de Mahajamba (Bassin de Mahajanga).
  Which describes the geology, stratigraphy and dinosaurian remains recovered between the bays of Bombetoka and Mahajamba (again, no marine reptiles).

With the latter two articles having been authored from within Madagascar's own Université d'Antananarivo, searching their library might not be a bad next place to turn to...

[pachy-pleuro-whatnot-odon]

So I did some more searching online and came across this site, hosted by the University of Antananarivo in Madagascar, that supposedly brings together Master and doctorate theses from all universities in the country. All of these available for access in PDF-format. Although in French, it would therefore seem an excellent of local, up-to-date and possibly unpublished data. And, indeed, it seems like the site contains a wealth of information on the geology, stratigraphy and palaeoecology of Madagascar, including interesting discussions on site taphonomy, dinosaurs and mammals. However, I haven't been able to come across anything related to marine reptiles

[caterpillar]

Thanks for the link

[pachy-pleuro-whatnot-odon]

Just thought I'd bump up this thread again by sharing some photographs of Madagascan marine reptile material I've come across commercially.

 

Two different elasmosaur podials (one a humerus, the other likely a femur) from Toliara/Tuléar in southwestern Madagascar. According to PaleoBioDB, Cretaceous marine deposits in this area range from Aptian through Maastrichtian in age.

 

 

 

 

 

 

 

 

 

 

 

 

Plesiosaur vertebrae of unknown date and provenance, but likely from the same - or a close-by - locality as the above podials, seeing as their similar conservation and them being sold by the same vendor. Though it's hard to make out the telltale signs that would allow the larger specimen to be identified as plesiosaurian, the smaller one is indeed a plesiosaur.

 

 

 

 

 

 

 

 

Section of an ichthyosaur jaw with three teeth in it, Majunga-basin of northwestern Madagascar. Seller described them as ophthalmosaurid and Middle Jurassic. However, tooth morphology - that is, smooth enamel to slight plicidentine on the crown and folds on the root - is more typical of Early Jurassic species.

[pachy-pleuro-whatnot-odon]

On 4/2/2021 at 10:43 PM, pachy-pleuro-whatnot-odon said:

 

Section of an ichthyosaur jaw with three teeth in it, Majunga-basin of northwestern Madagascar. Seller described them as ophthalmosaurid and Middle Jurassic. However, tooth morphology - that is, smooth enamel to slight plicidentine on the crown and folds on the root - is more typical of Early Jurassic species.

 

Just wanted to remark upon this apparent contradiction between Late Triassic/Early Jurassic morphology versus the supposed Middle Jurassic origin of this jaw-section by saying that 1) most finds from the Majunga-basin dating to the Middle Jurassic appear to be terrestrial sites, according to PaleoBioDB, with fully marine environments only coming about during the Late Jurassic and Early Cretaceous (though lagoonal environments seem to have existed in the surroundings of the basin during Early Jurassic times); but that 2) a Late Jurassic, or even Early Cretaceous, date for a morphologically Late Triassic/Early Jurassic ichthyosaur might not necessarily be the anachronism that it may seem: Malawania anachronus is an Early Cretaceous (Hauterivian or Barremian) ichthyosaur from Iraq with closer affinities to the Late Triassic/Early Jurassic genus Ichthyosaurus, rather than to at that point more common family of ophthalmosauridae (once believed to be the sole surviving ichthyosaur family of the Cretaceous).

 

Though of uncertain provenance, M. anachronus is firmly dated to the Early Cretaceous based on dinoflagellate cysts (Muderongia staurota), pollen and spores detected in the sediments that encased its remains (read up on it here and here). And while M. anachronus' survival is argued to be the result of it having lived in a "partially enclosed marine basin" Naish (2013) refers to as a "safe haven", the same may be true for Madagascar, which seems to have formed the southeastern margin of an interior seaway for much of the Jurassic. Could it be that there were more of these anachronistic, morphotypically early ichthyosaurian survival species spread out across the globe along the margins of the Tethys ocean?

Edited June 3, 2021 by pachy-pleuro-whatnot-odon

[pachy-pleuro-whatnot-odon]

On 6/3/2021 at 4:23 PM, pachy-pleuro-whatnot-odon said:

Though of uncertain provenance, M. anachronus is firmly dated to the Early Cretaceous based on dinoflagellate cysts (Muderongia staurota), pollen and spores detected in the sediments that encased its remains (read up on it here and here). And while M. anachronus' survival is argued to be the result of it having lived in a "partially enclosed marine basin" Naish (2013) refers to as a "safe haven", the same may be true for Madagascar, which seems to have formed the southeastern margin of an interior seaway for much of the Jurassic. Could it be that there were more of these anachronistic, morphotypically early ichthyosaurian survival species spread out across the globe along the margins of the Tethys ocean?

 

Ben G Thomas recently did a wonderful video-issue on Malawania anachronus, which can be found here: