A Complete Guide to the Dinosaurs and Prehistoric Life of Madagascar’s Maevarano Formation

During the Late Cretaceous Period, some 70 million years ago, life in Madagascar was just as strange as it is today. Giant frogs, vegan crocodiles, and cannibal dinosaurs were some of the unique species that called Madagascar home.

Fossils from Cretaceous Madagascar were first discovered at the Maevarano geological formation in 1895. It would take nearly a century for Maevarano’s strange fauna to be fully realized, starting with expeditions in 1993 organized by Canadian paleontologist David Krause. Krause’s expeditions discovered many of Maevarano’s unique animals and opened the floodgates of paleontology in Madagascar.

Maevarano’s species were evolutionary by-products of Madagascar’s isolation. As is the case in the present, Madagascar’s island status allowed for species to evolve separately from their mainland counterparts, thereby developing unique traits. This article will be dedicated to introducing the bizarre animals of Maevarano and some facts about them. For the purposes of clarity, I will stick to the most notable species and list any others at the end of the article. With that note, allow me to be your guide to Cretaceous Madagascar!

Droughts & Floods: The Climate of Maevarano

The Maevarano Formation dates to the Maastrichtian age of the Late Cretaceous Period, between 70 and 65 million years ago. Fossil sites from the Maastrichtian are relatively rare, making Maevarano one of the best glimpses at life just before the extinction of the dinosaurs. At this time, Madagascar had already become an island after separating from India some 18 million years prior[i]. The climate of Cretaceous Madagascar was highly seasonal, with long dry seasons interspersed by intense wet seasons. Droughts were common, as evidenced by rocks found throughout Maevarano that form in arid conditions[ii].

Maevarano was an extensive floodplain intersected by large rivers[iii]. During dry seasons, thirsty animals converged on dried riverbeds in search of water. Occasionally, these animals were unsuccessful in their quest for water and died in the ancient riverbeds. When the rains returned, they pushed the bodies of the animals downstream, eventually leading to the formation of mass burial sites. These bonebeds, which often contain numerous species buried on top of each other, highlight the treacherous climate of Maevarano during the Cretaceous.

Meet the Species of an Island Nation: Dinosaurs

Majungasaurus crenatissimus: Majungasaurus was an 8-meter-long theropod whose ferocity compensated for its lack of height! One of the most well-studied abelisaurid dinosaurs, Majungasaurus had a short and bumpy snout, arms smaller than T-rex, and a small horn atop its skull. Make no mistake, Majungasaurus was no peaceful unicorn. With teeth that shed every few months, Majungasaurus was the top predator of Maevarano, eating everything from large sauropods to cannibalizing others of its own kind[iv][v].

Masiakasaurus knopfleri: Another strange abelisaurid, Masiakasaurus was a diminutive predator named after the lead singer of the Dire Straits, Mark Knopfler. The lower jaw of the two-meter-long carnivore was peculiar, as its frontmost teeth protruded out from the jaw. Why Masiakasaurus developed this trait is unclear, though it may have helped secure small, slippery prey such as fish and a certain amphibian featured later in this article…

Rahonavis ostromi: A dromaeosaurid – or raptor – the size of a pigeon, Rahonavis is one of the more unusual dinosaurs from Madagascar. The presence of rudimentary wings has led some paleontologists to theorize that Rahonavis was capable of flight, though this has been debated[vi]. In either scenario, Rahonavis very much looks like a bird, demonstrating how little difference there is between some small dinosaurs and prehistoric birds.

Rapetosaurus & Vahiny: Two titanosaurian sauropods, Rapetosaurus and Vahiny were the largest herbivores on the island. Rapetosaurus was the more common of the two, with numerous specimens ranging from 40-day-old babies to a few fragmentary adults. Vahiny was much rarer and is only known from a handful of bones, though they are sufficient to establish the two as separate genera.

Unnamed Ankylosaurid: Two teeth discovered in 1926 were initially identified as a subspecies of Stegosaurus, though have since been re-identified as belonging to an ankylosaur[vii]. Unfortunately, no other remains of this dinosaur have been discovered. I would be willing to bet that our mystery ankylosaur was a strange little dinosaur, given the recent discovery of other ankylosaurs from southern continents (see: The Growing Family of Southern Armoured Dinosaurs)

Birds:

Falcatakely forsterae: One of the newest species from Maevarano, Falcatakely was part of an ancient bird lineage known as the Enantiornithines. While this lineage went extinct with the dinosaurs at the end of the Cretaceous, some of Falcatakely’s traits were like modern birds, most notably its toucan-shaped beak. The presence of a single tooth on its beak adds another wrinkle to the mix, making Falcatakely a strange cross between modern and extinct birds.

Crocodiles:

Simosuchus clarki: In a land dominated by strange animals, Simosuchus may be the strangest. A meter-long, pug-nosed crocodile with a stubby tail, Simosuchus went against its crocodilian ancestry by becoming a vegetarian. That’s right: Simosuchus was a vegan crocodile. Despite what you may think, Simosuchus wasn’t entirely an outlier, as a few other prehistoric crocodiles developed similar diets.

Mahajangasuchus insignis: The inverse of Simosuchus was Mahajangasuchus, a larger, predatory crocodile. Despite its ancestors being mostly terrestrial, Mahajangasuchus transitioned back to semiaquatic behaviours[viii]. With a broad skull and blunt teeth, Mahajangasuchus would have made for a ferocious predator if you ventured too close to the water…

Amphibians:

Beelzebufo ampinga: A challenger for the strangest animal present at Maevarano, Beelzebufo was no ordinary frog. Measuring 40 centimetres and weighing 9 pounds, Beelzebufo was the largest frog to have ever lived. The ‘devil frog’ would have been a terrifying sight, especially for the baby dinosaurs that Beelzebufo could fit inside its mouth…

Mammals:

Vintana & Adalatherium: For years, the Gondwanatheres – a mysterious group of mammals from the Cretaceous and Paleogene – were only known from teeth. That has changed in recent years with the discoveries of Vintana and Adalatherium, two Gondwanatheres with well-preserved skeletons. These animals were badger-sized vegetarians that may have practised nocturnal behaviours to survive in the undergrowth of Cretaceous Madagascar[ix].

Other Animals:

Fish, snakes, and turtles are well represented in the rocks of Maevarano. The largest snake was Madtsoia, which grew to lengths of 8 meters long and may have constricted its prey[x]. In 2021, fossil material of the turtle Sahonachelys was described, which indicated that it was a suction-feeder of aquatic prey (like Beelzebufo tadpoles, perhaps?)[xi]. Terrestrial crocodiles were present, including the “dog-croc” Araripesuchus. A few assorted birds have also been discovered, including the genus Vorona. Surprisingly, no pterosaurs have been discovered in Maevarano, though future excavations may reveal their presence.

The animals of the Maevarano Formation provide a unique glimpse of life at the end of the Cretaceous. Our collection of animals took advantage of their island paradise, evolving into bizarre forms not found anywhere else in the world. When the dinosaurs went extinct 66 million years ago, the odd fauna of Madagascar disappeared alongside their mainland counterparts.

Thank you for reading today’s article! If you’d like to know more about Beelzebufo and if it could eat dinosaurs, read about “Madagascar’s Devilishly Large Frog” here at Max’s Blogosaurus!

I do not take credit for any images found in this article.

Header Image Courtesy of the Ultimate Dinosaurs Travelling Exhibit and Riley Black, found here

Works Cited:

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[i] Pickrell, John. Weird Dinosaurs. Columbia University Press, 2017.

[ii] Krause, David W, and Raymond R Rogers. “Dinosaurs Found in Mass Grave Died of Drought.” Scientific American, 1 May 2014, https://www.scientificamerican.com/article/dinosaurs-found-in-mass-grave-died-of-drought/.

[iii] Papini, Mauro, and Marco Benvenuti. “Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas: A Discussion.” The Journal of Geology, vol. 109, no. 5, 2001, pp. 669–673., https://doi.org/10.1086/321963.

[iv] D’Emic, Michael D., et al. “Correction: Evolution of High Tooth Replacement Rates in Theropod Dinosaurs.” PLOS ONE, vol. 14, no. 12, 2019, https://doi.org/10.1371/journal.pone.0226897.

[v] Brusatte, Stephen. Dinosaur Paleobiology. Wiley-Blackwell, 2012.

[vi] Serrano, Francisco J., and Luis M. Chiappe. “Independent Origins of Powered Flight in Paravian Dinosaurs?” Current Biology, vol. 31, no. 8, 2021, https://doi.org/10.1016/j.cub.2021.03.058.

[vii] Raven, Tom, and Susannah C. Maidment. “A New Phylogeny of Stegosauria (Dinosauria, Ornithischia).” 2018, https://doi.org/10.31233/osf.io/9atjd.

[viii] Wilberg, Eric W., et al. “Evolutionary Structure and Timing of Major Habitat Shifts in Crocodylomorpha.” Scientific Reports, vol. 9, no. 1, 2019, https://doi.org/10.1038/s41598-018-36795-1.

[ix] Brusatte, Steve, et al. The Rise and Reign of the Mammals: A New History, from the Shadow of the Dinosaurs to Us. Mariner Books; Picador, 2022.

[x] Laduke, Thomas C., et al. “A Late Cretaceous (Maastrichtian) Snake Assemblage from the Maevarano Formation, Mahajanga Basin, Madagascar.” Journal of Vertebrate Paleontology, vol. 30, no. 1, 2010, pp. 109–138., https://doi.org/10.1080/02724630903409188.

[xi] Joyce, Walter G., et al. “A New Pelomedusoid Turtle, Sahonachelys Mailakavava, from the Late Cretaceous of Madagascar Provides Evidence for Convergent Evolution of Specialized Suction Feeding among Pleurodires.” Royal Society Open Science, vol. 8, no. 5, 2021, https://doi.org/10.1098/rsos.210098.