The Evolution of Filter Feeding and Gigantism in the Ocean
We are living amongst the time of giants.
The baleen whales are larger than any known dinosaur and ANY animal that has come before them. The Blue whale itself, is capable of weighing 180 metric tonnes (the same weight as 30 African elephants stacked on top of each other) and can be longer than a basketball court… But why is this so?
Many will tell you about how it has something to do with predator avoidance or how the restraints of gravity are significantly less restrictive in the ocean, but the most important reason for the whales’ size has something to do with the icy inhospitable continent of Antarctica...
The Antarctic Circumpolar Current is one of the most productive upwelling’s the world has ever seen. This, and similar upwelling’s found around the globe (and specifically around arctic areas), generate a humungous nutrient glut that creates masses of food for these mighty animals. The ocean has NEVER been quite as productive. But even this isn't enough: it all comes down to a unique and highly adaptable structure hanging from the top of their mouths...
Baleen.
These hairy fringes of keratin are vital in obtaining their diminutive prey.
Throughout evolutionary history, a number of animals have adapted the same strategy as the Blue whale: to filter large amounts of water/sediment (via their teeth or other structures) for small organisms (such as krill) that thrive within them.
Some creatures grew to HUGE sizes, from the bizarre Anomolcarid Aegirocassis (a two metre long shrimp-like creature that thrived in the Ordovician oceans 480 million years ago), to giant filter feeding crocodiles that independently evolved at least TWICE and grew to more than ten metres in length.
The Shrimp-like “Aegirocassis”
The earliest known “giant” filter feeder to date, this two metre long shrimp-like arthropod has no living relatives alive on the earth today. If aliens abducted me right now, i would expect them to look like this. Belonging to the enigmatic predator group that includes one of the very first predators that ever evolved (Anomalocaris); two metres in length may not seem big, but 480 million years ago, complicated predator-prey relationships were only just evolving.
According to the authors, ribbon like structures attached to an upper row of flaps, along with frontal spines that made a mesh like arrangement that could have allowed the animal to filter feed. The anomalocarids went extinct about 400 million years ago in the hot-house of the Earliest Devonian.
The very first “giant” filter feeder with a backbone was the 8 metre long Titanichthys, a placoderm fish with a heavily armoured skull that lived 360 million years ago. It approached its much more famous Dunkleosteus in size but rather than have the sharp, garden shear mouth plates of its cousin, it had comparatively small and blunt mouth plates and most likely used them to filter-feed.
This is a-bit of a sidestep, but definitely worth mentioning.
Ah yes, Triassic reptiles. They are truly strange beasts. Henodus is a 225 million year old freshwater placodont (“tablet teeth”) superficially resembling a turtle in almost every single way, but having closer evolutionary affinities to plesiosaurs. It was a metre in length and definitely not gigantic for the period, but it filter feed with baleen-like denticles along the jaw. With unique neck bones and musculature, it sucked water in rapidly over its baleen like structures.
The massive extinction event that took the dinosaurs wiped out numerous long-lived lineages. These included the likes of the the bi-plane sized pterosaurs, the incredibly diverse marine reptiles including the plesiosaurs and mosasaurs, multiple lineages of bird groups and a bizarre group of fish that had taken to the ecological niche of a baleen whale.
These fish were the Pachycormiforms, gigantic filter feeders that approached the size of Humpback whales in the mid Jurassic Period. They thrived for 100 million years and we’ll be focusing on the largest of these: the 165 million year old Leedsichthys.
What has been found of these giant fish (from the fossil record) has shown that they used their gill arches (which were lined by gill-rakers and a distinctive system of fragile bone plates) to presumably filter plankton from the Mesozoic seas.
To date, over seventy individuals have been discovered and every single one has been found without any teeth at all. Filter feeding strategies enable animals to get humungous; Leedsichthys was the largest bony fish ever discovered. Some evidence seems to indicate it was a bottom feeder, slurping up sediment and tiny particles of food in a similar manner to modern gray whales. Leedsichthys was the beginning of a long line of filter feeding pachycormid fish that would continue into the Late Cretaceous and end with a giant fireball in the sky, just like the non-avian dinosaurs.
I love the idea of Stomatosuchus. It seems to defy belief and has been a part of palaeontology folklore for the better part of 100 years, ever since an allied bombing raid destroyed the holotype (in the Munich Museum) in 1944.
Stomatosuchus was a 10 metre long filter feeding Crocodyliform that existed in Egypt 100 – 95 million years ago and its feeding ecology has been up for mass debate. The lower jaw appeared toothless, with the upper studded with only small conical teeth. Its jaw is hugely reminiscent of baleen whales and has been reinterpreted as having a gular sac (similar to pelicans alive today) gulping gigantic quantities of water. It was one of the largest crocodyliforms that ever existed.
The Toothy Plesiosaur “Morturneria”
Mortuneria was a toothy, long necked plesiosaur and one of the last giant marine reptiles, being roughly 8 metres in length. It is hugely difficult to interpret the feeding ecology of extinct animals, especially when you consider that we’re having difficulty understanding modern animals with flesh and skin.
I have issues with the palaeo-ecological reconstruction of Mortuneria (namely that we simply don't have enough to make this interpretation). The authors state that the “downward-curving teeth of the lower jaw… the arched palate and U-shaped lower jaw” (amongst a few other things) allowed it to strain small animals out of a scoopful of sediment like a modern gray whale. According to the literature today, Mortuneria is yet another ancient filter feeder.
Next up, we’ll look at gigantism and filter feeding in the Cenozoic (65 million years to the present).
I wouldn't exactly call the American paddlefish (Polyodon spathula) a “giant”, but they utilise a unique strategy for obtaining their food. There are two species alive today, including the monstrous and critically endangered Chinese Paddlefish, which can reach up to an insane 7 metres in length. It is a strict piscivore, but the vulnerable American Paddlefish has its origins from the early Cretaceous, although it is unknown when filter feeding came into play. The largest specimen ever caught was over 2 metres in length and weighed 90 kilograms! For a freshwater fish, that is humungous.
The gill rakers of American paddlefish are composed of extensive comb-like filaments, which in addition to aspects of their skull and their jaw, allow for filtration of zooplankton in the murky water. Adults have completely lost any evidence of teeth. Electroreception appears to have largely replaced vision as a primary sense, which indicates a reliance on these electro-receptors for detecting prey. This is an incredible relict fish that is on the verge of extinction.
There are three extant species of filter feeding shark: the largest fish in the ocean, the Whale shark (Rhincodon typus), the similarly sized Basking Shark (Cetorhinus maximus) and the ever-elusive Megamouth shark (Megachasma pelagios). All three diverged from completely separate families and converged on similar shapes and strategies to filter feed.
Now remember, the fossil record is hugely biased. Finding evidence of these giants is incredibly difficult. Despite their huge size, their teeth are minuscule but there appears to be evidence of the Megamouth sharks dating back some 42 million years ago, with the other two giants appearing within 10-15 million years thereafter.
Lets start with Whale sharks, as they are the largest of all living fish, approaching the size of a modern Humpback whale.
SIDE NOTE: There are unsubstantiated reports of them getting even bigger than 12 metres. In 1868, the Irish scientist Edward Perceval Wright observed specimens reaching 21 metres in length. But can we trust Irish scientists?
Whale sharks swim fin and tail with gigantism and filter feeding. They have jaws that are more than 1.5 metres in length; raked with 350 rows of tiny teeth (possibly vestigial?) along with ten distinct “filter pads” that facilitate filter feeding.
Feeding for all three of these unique sharks occurs either by ram filtration (in which the animal opens its jaws wide and swims forward, pushing water and delicious morsels of food into its mouth) or by active suction feeding (in which the animal opens/shuts its mouth, sucking in water that is then expelled through the gills). The Basking shark relies only on the water it pushes through its gills by swimming; alternatively, the Megamouth shark and Whale shark can suck or pump water through their massive gill-slits.
Of all three sharks, the Megamouth is undoubtedly the most mysterious. It was discovered on November 15, 1976 when a specimen became entangled with the anchor of an American naval ship off the coast of Hawaii and since then, only 100 specimens have ever been found.
We’ve talked about filter-feeding crocodiles before (with the 100 million year old Stomatosuchus) but by far one of the most bizarre reptiles that ever existed within the Amazon jungle was the 12 metre long FILTER FEEDING caiman, the duck faced Mourasuchus. The bizarre anatomy of the mid-late Miocene (6-10 million year old) Mourasuchus has been rigorously debated.
Its rostrum was broad and dorso-ventrally flattened, with slender mandibles and a short symphysis (as seen with baleen whales) and small teeth. These characteristics would make it a suitable candidate for a “filter-feeding” way of capturing prey, with an envisaged “gular sac” (reminiscent of pelicans) that would function for this straining technique (akin to Stomatosuchus).
Mourasuchus was a dead end experiment in the evolution of crocodiles. The long-term environmental stability of the Amazon would have provided the perfect environment for these bizarre Miocene filter-feeding crocodiles, but monumental change in the earth would soon occur and by the Pliocene, hydrographic changes linked to the Andean uplift would kill off Mourasuchus and its associated gigantic kin.
Manta Rays are the largest of all the rays, reaching up to 7 metres in width. There are two extant species and these enigmatic rays date roughly back to the latest Oligocene, 23 million years ago. In a manner similar to Basking sharks, the Manta swims in a circular motion around its zooplankton prey until they form a dense cluster; it then zooms through and gulps them all up.
While feeding, Mantas focus on minuscule organisms; these are then herded into their gaping mouths via the use of their cephalic fins and subsequently collected between the gill arches. Despite their immense size, they are still considered vulnerable.
A single dead manta ray is estimated to be worth between $40-$500 dollars in your average fish market. By contrast, a single manta ray may contribute more than 1 million dollars to the global tourism trade during its lifetime.
As one of Antarctica’s top predators, the Leopard seal is the second largest seal in the world (imagine a mermaid-dog the size of a racehorse!). The fossil record is hugely patchy when it comes to seal evolution, so if you have questions, ask @palaeo_james_rule because that thing is a mess, but this lineage most likely originated in the MIDDLE Pliocene.
These “suckers” engorge themselves on penguins, squid, fish and are also capable of filtering out krill between their trident shaped teeth. It's the equivalent of a lion slurping up ants on the Serengeti and one individual was necropsied with 10,000 krill in its stomach. Krill are clearly critical to the survival to these giant seals in the Southern ocean.
Filter feeding has enabled some creatures in evolutionary history to get to gargantuan sizes, but none have readily approached the size of the Blue whale today. It is entirely possible that the Blue whale has hit a theoretical size limit and it owes it all to the highly adaptable material you can find in your hair and fingernails and also, in the upper palate of all baleen whales; keratin.
Did i miss out on any other prehistoric/modern filter feeders? The flying reptile Pterodaustro comes to mind, but they aren't exactly “gigantic”. List them down into the comments! I want to know!
Marx, F.G., Hocking, D.P., Park, T., Ziegler, T., Evans, A.R., and Fitzgerald, E.M.G. (2016). Suction feeding preceded filtering in baleen whale evolution. Mem. Mus. Vic. 75, 71–82.
Edgecombe GD. Palaeontology: In a flap about flaps. Curr Biol. 2015;25(12):R503–6.
Boyle, J., & Ryan, M. (2017). New information on Titanichthys (Placodermi, Arthrodira) from the Cleveland Shale (Upper Devonian) of Ohio, USA. Journal of Paleontology, 91(2), 318-336. doi:10.1017/jpa.2016.136
R. Collin, C. M. Janis, Morphological constraints on tetrapod feeding mechanisms: Why were there no suspension feeding marine reptiles?, in Ancient Marine Reptiles, J. M. Calloway, E. L. Nicholls, Eds. (Academic Press, San Diego, CA, 1997), pp. 451–466.
Liston, J, Newbrey, M., Challands, T.and Adams, C.(2013) Growth, age and size of the Jurassic pachycormid Leedsichthys problematicus (Osteichthyes: Actinopterygii). In: Arratia, G., Schultze, H. and Wilson, M. (eds.) Mesozoic Fishes 5 – Global Diversity and Evolution. Verlag Dr. Friedrich Pfeil: München, Germany, pp. 145-175. ISBN 9783899371598
Turner AH (2004) Crocodyliform biogeography during the Cretaceous: evidence of Gondwanan vicariance from biogeographical analysis. Proceedings of the Royal Society B 271: 2003–2009.
(2017) Cranial anatomy of Morturneria seymourensis from Antarctica, and the evolution of filter feeding in plesiosaurs of the Austral Late Cretaceous, Journal of Vertebrate Paleontology,37:4,
Grande, L. and Bemis, W.E. (1991) Osteology and phylogenetic relationship of fossil and recent paddlefishes (Polyodontidae) with comments on the interrelationships of Acipenseriformes. J. Vert. Paleo. 11(Suppl.1), 1–121.
Motta, Philip J., et al. "Feeding anatomy, filter-feeding rate, and diet of whale sharks Rhincodon typus during surface ram filter feeding off the Yucatan Peninsula, Mexico." Zoology113.4 (2010): 199-212.
Bona, Paula, Federico J. Degrange, and Marta S. Fernández. "Skull anatomy of the bizarre crocodylian Mourasuchus nativus (Alligatoridae, Caimaninae)." The Anatomical Record296.2 (2013): 227-239.
The baleen whales are larger than any known dinosaur and ANY animal that has come before them. The Blue whale itself, is capable of weighing 180 metric tonnes (the same weight as 30 African elephants stacked on top of each other) and can be longer than a basketball court… But why is this so?
Many will tell you about how it has something to do with predator avoidance or how the restraints of gravity are significantly less restrictive in the ocean, but the most important reason for the whales’ size has something to do with the icy inhospitable continent of Antarctica...
The Antarctic Circumpolar Current is one of the most productive upwelling’s the world has ever seen. This, and similar upwelling’s found around the globe (and specifically around arctic areas), generate a humungous nutrient glut that creates masses of food for these mighty animals. The ocean has NEVER been quite as productive. But even this isn't enough: it all comes down to a unique and highly adaptable structure hanging from the top of their mouths...
Baleen.
These hairy fringes of keratin are vital in obtaining their diminutive prey.
 |
| NEXT UP ON MY STRANGE ADDICTION: "I can't help but eat a metric tonne of krill every day" sobbed the blue whale. " I have a severe problem". Image via Carl Buell |
Throughout evolutionary history, a number of animals have adapted the same strategy as the Blue whale: to filter large amounts of water/sediment (via their teeth or other structures) for small organisms (such as krill) that thrive within them.
 |
| From nom-nom, to slurpy-slurp to gulpy-gulp: Image via Marx et al. 2016/Memoirs of Museum Victoria, displaying difference in skull shape that facilitated filter feeding in baleen whales. |
Some creatures grew to HUGE sizes, from the bizarre Anomolcarid Aegirocassis (a two metre long shrimp-like creature that thrived in the Ordovician oceans 480 million years ago), to giant filter feeding crocodiles that independently evolved at least TWICE and grew to more than ten metres in length.
It’s going to be a bumpy evolutionary ride as we travel back in time to look at how filter-feeding and gigantism have swam fin and tail with each other for almost half a billion years.
First up, lets look at the invertebrate filter feeder from the Ordovician: Aegirocassis…
First up, lets look at the invertebrate filter feeder from the Ordovician: Aegirocassis…
 |
| Flying Spaghetti monster eat your heart out... Image via by Hyrotrioskjan on Deviant Art |
The Shrimp-like “Aegirocassis”
The earliest known “giant” filter feeder to date, this two metre long shrimp-like arthropod has no living relatives alive on the earth today. If aliens abducted me right now, i would expect them to look like this. Belonging to the enigmatic predator group that includes one of the very first predators that ever evolved (Anomalocaris); two metres in length may not seem big, but 480 million years ago, complicated predator-prey relationships were only just evolving.
According to the authors, ribbon like structures attached to an upper row of flaps, along with frontal spines that made a mesh like arrangement that could have allowed the animal to filter feed. The anomalocarids went extinct about 400 million years ago in the hot-house of the Earliest Devonian.
 |
| Titanicthys: the old person version of Dunkleosteus. Image via User: Apokryltaros on Wikipedia |
The Armoured Fish “Titanichthys”
The very first “giant” filter feeder with a backbone was the 8 metre long Titanichthys, a placoderm fish with a heavily armoured skull that lived 360 million years ago. It approached its much more famous Dunkleosteus in size but rather than have the sharp, garden shear mouth plates of its cousin, it had comparatively small and blunt mouth plates and most likely used them to filter-feed.
 |
| "If I don't save the wee turtles, who will?!"... wait, they aren't turtles? Why is the Triassic so confusing? Image via Nobu Tamura |
The Turtle Mimic “Henodus”
This is a-bit of a sidestep, but definitely worth mentioning.
Ah yes, Triassic reptiles. They are truly strange beasts. Henodus is a 225 million year old freshwater placodont (“tablet teeth”) superficially resembling a turtle in almost every single way, but having closer evolutionary affinities to plesiosaurs. It was a metre in length and definitely not gigantic for the period, but it filter feed with baleen-like denticles along the jaw. With unique neck bones and musculature, it sucked water in rapidly over its baleen like structures.
 |
| Im pretty sure Nigel Marvin died in that "Sea Monsters" documentary. Did he touch one of these animals? Irrespective, they definitely did not reach the purported 28 metre lengths stated by that documentary. Image by ABelov2014 on Deviant Art. |
The Giant Fish, “Pachycormidae”: “Leedsichthys”
These fish were the Pachycormiforms, gigantic filter feeders that approached the size of Humpback whales in the mid Jurassic Period. They thrived for 100 million years and we’ll be focusing on the largest of these: the 165 million year old Leedsichthys.
What has been found of these giant fish (from the fossil record) has shown that they used their gill arches (which were lined by gill-rakers and a distinctive system of fragile bone plates) to presumably filter plankton from the Mesozoic seas.
To date, over seventy individuals have been discovered and every single one has been found without any teeth at all. Filter feeding strategies enable animals to get humungous; Leedsichthys was the largest bony fish ever discovered. Some evidence seems to indicate it was a bottom feeder, slurping up sediment and tiny particles of food in a similar manner to modern gray whales. Leedsichthys was the beginning of a long line of filter feeding pachycormid fish that would continue into the Late Cretaceous and end with a giant fireball in the sky, just like the non-avian dinosaurs.
 |
"Where did the sun go?" asked the diver, gleefully unaware of his impending death. Image by: Unknown. If you know the artist, please let me know.
The Pelican Crocodile “Stomatosuchus"
|
I love the idea of Stomatosuchus. It seems to defy belief and has been a part of palaeontology folklore for the better part of 100 years, ever since an allied bombing raid destroyed the holotype (in the Munich Museum) in 1944.
Stomatosuchus was a 10 metre long filter feeding Crocodyliform that existed in Egypt 100 – 95 million years ago and its feeding ecology has been up for mass debate. The lower jaw appeared toothless, with the upper studded with only small conical teeth. Its jaw is hugely reminiscent of baleen whales and has been reinterpreted as having a gular sac (similar to pelicans alive today) gulping gigantic quantities of water. It was one of the largest crocodyliforms that ever existed.
 |
| “My god! It’s like a party in my mouth and everyone’s invited". Via O’Keefe et al. 2017, of the face profile of Morturneria. |
The Toothy Plesiosaur “Morturneria”
Mortuneria was a toothy, long necked plesiosaur and one of the last giant marine reptiles, being roughly 8 metres in length. It is hugely difficult to interpret the feeding ecology of extinct animals, especially when you consider that we’re having difficulty understanding modern animals with flesh and skin.
I have issues with the palaeo-ecological reconstruction of Mortuneria (namely that we simply don't have enough to make this interpretation). The authors state that the “downward-curving teeth of the lower jaw… the arched palate and U-shaped lower jaw” (amongst a few other things) allowed it to strain small animals out of a scoopful of sediment like a modern gray whale. According to the literature today, Mortuneria is yet another ancient filter feeder.
Next up, we’ll look at gigantism and filter feeding in the Cenozoic (65 million years to the present).
 |
| Larry the dentist would later catch pneumonia and die shortly after posing with his fish. Photo courtesy of Arkansas Game and Fish Commission |
The American Paddlefish
I wouldn't exactly call the American paddlefish (Polyodon spathula) a “giant”, but they utilise a unique strategy for obtaining their food. There are two species alive today, including the monstrous and critically endangered Chinese Paddlefish, which can reach up to an insane 7 metres in length. It is a strict piscivore, but the vulnerable American Paddlefish has its origins from the early Cretaceous, although it is unknown when filter feeding came into play. The largest specimen ever caught was over 2 metres in length and weighed 90 kilograms! For a freshwater fish, that is humungous.
The gill rakers of American paddlefish are composed of extensive comb-like filaments, which in addition to aspects of their skull and their jaw, allow for filtration of zooplankton in the murky water. Adults have completely lost any evidence of teeth. Electroreception appears to have largely replaced vision as a primary sense, which indicates a reliance on these electro-receptors for detecting prey. This is an incredible relict fish that is on the verge of extinction.
 |
"AAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH". Image via Drop Science on Tumblr
The Filter Feeding sharks
Now remember, the fossil record is hugely biased. Finding evidence of these giants is incredibly difficult. Despite their huge size, their teeth are minuscule but there appears to be evidence of the Megamouth sharks dating back some 42 million years ago, with the other two giants appearing within 10-15 million years thereafter.
Lets start with Whale sharks, as they are the largest of all living fish, approaching the size of a modern Humpback whale.
SIDE NOTE: There are unsubstantiated reports of them getting even bigger than 12 metres. In 1868, the Irish scientist Edward Perceval Wright observed specimens reaching 21 metres in length. But can we trust Irish scientists?
Whale sharks swim fin and tail with gigantism and filter feeding. They have jaws that are more than 1.5 metres in length; raked with 350 rows of tiny teeth (possibly vestigial?) along with ten distinct “filter pads” that facilitate filter feeding.
 |
| "AAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH". Image via David Doubilet |
Feeding for all three of these unique sharks occurs either by ram filtration (in which the animal opens its jaws wide and swims forward, pushing water and delicious morsels of food into its mouth) or by active suction feeding (in which the animal opens/shuts its mouth, sucking in water that is then expelled through the gills). The Basking shark relies only on the water it pushes through its gills by swimming; alternatively, the Megamouth shark and Whale shark can suck or pump water through their massive gill-slits.
Of all three sharks, the Megamouth is undoubtedly the most mysterious. It was discovered on November 15, 1976 when a specimen became entangled with the anchor of an American naval ship off the coast of Hawaii and since then, only 100 specimens have ever been found.
 |
| "You think I'm weird? Just wait til they find my search history". Image via Dmitry Bogdanov |
The Duck-faced "Mourasuchus"
Its rostrum was broad and dorso-ventrally flattened, with slender mandibles and a short symphysis (as seen with baleen whales) and small teeth. These characteristics would make it a suitable candidate for a “filter-feeding” way of capturing prey, with an envisaged “gular sac” (reminiscent of pelicans) that would function for this straining technique (akin to Stomatosuchus).
Mourasuchus was a dead end experiment in the evolution of crocodiles. The long-term environmental stability of the Amazon would have provided the perfect environment for these bizarre Miocene filter-feeding crocodiles, but monumental change in the earth would soon occur and by the Pliocene, hydrographic changes linked to the Andean uplift would kill off Mourasuchus and its associated gigantic kin.
 |
The Giant Sea Pancake died shortly after being taken out of the water. NOTE: this image is actually of a model Giant sea pancake, used in a museum installation and not of one that was caught.
|
The Gliding Devil Fish
While feeding, Mantas focus on minuscule organisms; these are then herded into their gaping mouths via the use of their cephalic fins and subsequently collected between the gill arches. Despite their immense size, they are still considered vulnerable.
A single dead manta ray is estimated to be worth between $40-$500 dollars in your average fish market. By contrast, a single manta ray may contribute more than 1 million dollars to the global tourism trade during its lifetime.
 |
You don't make friends with salad. Image via Amos Nachoum
|
The Leopard of Antarctica
These “suckers” engorge themselves on penguins, squid, fish and are also capable of filtering out krill between their trident shaped teeth. It's the equivalent of a lion slurping up ants on the Serengeti and one individual was necropsied with 10,000 krill in its stomach. Krill are clearly critical to the survival to these giant seals in the Southern ocean.
Filter feeding has enabled some creatures in evolutionary history to get to gargantuan sizes, but none have readily approached the size of the Blue whale today. It is entirely possible that the Blue whale has hit a theoretical size limit and it owes it all to the highly adaptable material you can find in your hair and fingernails and also, in the upper palate of all baleen whales; keratin.
Did i miss out on any other prehistoric/modern filter feeders? The flying reptile Pterodaustro comes to mind, but they aren't exactly “gigantic”. List them down into the comments! I want to know!
References
Marx, F.G., Hocking, D.P., Park, T., Ziegler, T., Evans, A.R., and Fitzgerald, E.M.G. (2016). Suction feeding preceded filtering in baleen whale evolution. Mem. Mus. Vic. 75, 71–82.
Edgecombe GD. Palaeontology: In a flap about flaps. Curr Biol. 2015;25(12):R503–6.
Boyle, J., & Ryan, M. (2017). New information on Titanichthys (Placodermi, Arthrodira) from the Cleveland Shale (Upper Devonian) of Ohio, USA. Journal of Paleontology, 91(2), 318-336. doi:10.1017/jpa.2016.136
R. Collin, C. M. Janis, Morphological constraints on tetrapod feeding mechanisms: Why were there no suspension feeding marine reptiles?, in Ancient Marine Reptiles, J. M. Calloway, E. L. Nicholls, Eds. (Academic Press, San Diego, CA, 1997), pp. 451–466.
Liston, J, Newbrey, M., Challands, T.and Adams, C.(2013) Growth, age and size of the Jurassic pachycormid Leedsichthys problematicus (Osteichthyes: Actinopterygii). In: Arratia, G., Schultze, H. and Wilson, M. (eds.) Mesozoic Fishes 5 – Global Diversity and Evolution. Verlag Dr. Friedrich Pfeil: München, Germany, pp. 145-175. ISBN 9783899371598
Turner AH (2004) Crocodyliform biogeography during the Cretaceous: evidence of Gondwanan vicariance from biogeographical analysis. Proceedings of the Royal Society B 271: 2003–2009.
(2017) Cranial anatomy of Morturneria seymourensis from Antarctica, and the evolution of filter feeding in plesiosaurs of the Austral Late Cretaceous, Journal of Vertebrate Paleontology,37:4,
Grande, L. and Bemis, W.E. (1991) Osteology and phylogenetic relationship of fossil and recent paddlefishes (Polyodontidae) with comments on the interrelationships of Acipenseriformes. J. Vert. Paleo. 11(Suppl.1), 1–121.
Motta, Philip J., et al. "Feeding anatomy, filter-feeding rate, and diet of whale sharks Rhincodon typus during surface ram filter feeding off the Yucatan Peninsula, Mexico." Zoology113.4 (2010): 199-212.
Bona, Paula, Federico J. Degrange, and Marta S. Fernández. "Skull anatomy of the bizarre crocodylian Mourasuchus nativus (Alligatoridae, Caimaninae)." The Anatomical Record296.2 (2013): 227-239.
| Dewar, Heidi, et al. "Movements and site fidelity of the giant manta ray, Manta birostris, in the Komodo Marine Park, Indonesia." Marine Biology 155.2 (2008): 121 | |||
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