Pectinodon: Beast of the Week

Today we will be checking out a the bird-like dinosaur, Pectinodon bakkeri!  Pectinodon lived in what is now Wyoming, USA, during the latest Cretaceous period, about 66 million years ago.  Pectinodon is only known from highly fragmentary remains (mostly teeth) but is roughly estimated to have measured about six feet long from snout to tail when alive.  It would have eaten meat and possibly some plant material when it was alive.  Its genus name translates to "Comb Tooth" because of the deep serrations on the anterior edges of its teeth.  The species name is in honor of paleontologist, Dr. Robert Bakker.

My watercolor life restoration of Pectinodon bakkeri.  This animal was likely hunting smaller prey when it was alive, so cretaceous snakes could have been on the menu.

You may recognize Pectinodon by a different genus name, Troodon.  This is because Pectinodon was renamed Troodon during the 1980s.  Then in 2011, after further study, it was split back into its own taxa again.  In fact, the Troodon genus was split up into multiple taxa based on differences in morphology as well as the fact that all these fossils spanned an extremely long amount of time for only one genus of animal to have been living.  The "Troodon" dinosaur that lived during latest Cretaceous in the North American community, called the Hell Creek Formation, was Pectinodon.  The original name is still used to describe the family that all these smaller bird-like dinosaurs came from, Troodontidae.

Even though we don't have too much fossil material from Pectinodon, itself, we can make educated inferences about it based on its closest family members that we have more material from.  The teeth, which we do have, are sharp and possess deep serrations, but only on the edges that faced the back of the mouth.  The teeth are proportionally smaller than those of dromeosaurids, like Velociraptor or Acheroraptor.  Other troodontids are known to have had proportionally large, forward-facing eye sockets, suggesting they had good vision and may have even been able to see well in the dark.  It is this combination of features that lead many to believe troodontids, like Pectinodon, specialized in hunting small prey, like mammals, and small reptiles.

Photograph of one of Pectinodon's teeth.  Note how the anterior has deep serrations.

Pectinodon was likely covered in feathers when alive and probably would have looked like a bird to most of us at first glance if we encountered it today.  Its legs were probably long and slender, which would have allowed it to have run swiftly if it needed to.  This was probably a helpful trait since it would have been pursuing prey as well as avoiding potential predators, like the similarly sized, but more heavily armed, Acheroraptor, and even Tyrannosaurus rex (which was much faster and more agile as a subadult)   Being most active at night is also another way to avoid predation and is a tactic used by many animals today.  

Many animals evolve to be nocturnal to avoid predation.  During the Mesozoic most of the mammals were small and nocturnal to avoid the dinosaurs.  Naturally there will always be some predators that will evolve the same way.  The troodontids likely filled that niche.

Like dromaeosaurids ("raptor" dinosaurs, like Velociraptor, and Deinonychus) troodontids, like Pectinodon also had a retractable "killer claw" on each of their second toes, but theirs weren't as proportionally large as those of dromeosaurids.  This, combined with the traits already mentioned, further point to them specializing in taking much smaller prey.  I imagine troodontids stalking small mammals and reptiles in the thick brush at dusk or at night, using their senses of sight and hearing to zero in, and their long legs to clear tall foliage, then kicking and pinning  their target with their special claws when the time was right, and finally dismembering their meal with their serrated teeth.  Many modern predatory birds execute similar hunting behavior today in various ways.
 
References

Currie, P. (1987). "Theropods of the Judith River Formation". Occasional Paper of the Tyrrell Museum of Palaeontology 3: 52–60.

Holtz, Thomas R., Brinkman, Daniel L., Chandler, Chistine L. (1998) Denticle Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15. December 1998. pp. 159-166.

Larsson, H.C.E. 2001. Endocranial anatomy of Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution. pp. 19-33. In: Mesozioc Vertebrate Life. Ed.s Tanke, D. H., Carpenter, K., Skrepnick, M. W. Indiana University Press.

Larson D.W., Currie P.J., 2013, "Multivariate Analyses of Small Theropod Dinosaur Teeth and Implications for Paleoecological Turnover through Time", PLoS ONE 8(1): e54329. 

Nigersaurus: Beast of the Week

Nigersaurus taqueti was a sauropod dinosaur that lived in what is now Niger, Africa, during the Cretaceous Period, about 118 to 110 million years ago.  It measured only about thirty feet long which for a sauropod (largest kind of land animal of all time) is actually on the small side.

My reconstruction of Nigersaurus as it unknowingly disrupts a nesting Kaprosuchus. (or something very similar since these two taxa were actually separated by a few million years.)

Nigersaurus had a unique skull in that its mouth was wide and flat.  The skull actually resembles a vacuum cleaner head to be honest (if you google image search "vacuum cleaner head" and scroll down a bit, a picture of Nigersaurus actually will be one of the results.  No joke go try it).  Inside the mouth were six hundred tiny chisel-shaped teeth, the most teeth in any known sauropod, all lining the front of the mouth.  This arrangement was perfect for clipping low-lying vegetation, like a lawn mower.  Like any dinosaur, whenever one of Nigersaurus' teeth broke off or got worn down, a new one was right underneath ready to take its place.   

Nigersaurus taqueti skeletal mount reconstructed by Tyler Keillor and Stephen Godfrey.  This skeletal mount was unveiled at the National Geographic headquarters in 2007, when Nigersaurus made its public debut.

Nigersaurus had a relatively short neck for a sauropod.  Because of this, combined with the fact that its skull would have been naturally held facing the ground according to how its bones fit together, suggests it specialized in eating low growing plants rather than foliage off trees like some of its longer-necked relatives.  It's also worth noting, that Nigersaurus had eye sockets that were proportionally large and were positioned at the highest point of its skull, when it was in a neutral pose.  When alive you can see that it would have been able to see almost entirely around it at once, and would only need to move its head the slightest bit to either side, in order to see directly behind it or in front of it.  This may be an adaptation to keep lookout for predators without having to stop eating.  Since sauropods weren't particularly fast runners, Nigersaurus may have used its long tail as a weapon, or perhaps lived in herds for protection

Close up of Tyler Keillor's Nigersaurus skull.  You can really get a idea of how unique and specialized this dinosaur truly was!

Special thanks to paleo-artist, Tyler Keillor for allowing me to use images of his awesome skeletal reconstructions.  As always if you have a dinosaur or other prehistoric creature you would like to see covered comment below or let me know on twitter or facebook!

References

Sereno PC, Wilson JA, Witmer LM, Whitlock JA, Maga A, et al. (2007) Structural Extremes in a Cretaceous Dinosaur. PLoS ONE 2(11): e1230. [1] doi:10.1371/journal.pone.0001230.

Wilson, J. A. and Sereno, P. C. (2005). "Structure and Evolution of a Sauropod Tooth Battery". In Curry Rogers, K., and Wilson, J.A. (eds.), The Sauropods: Evolution and Paleobiology, University of California Press, Berkeley, ISBN 0-520-24623-3.

Anodontosaurus: Beast of the Week

This week we will be looking at a heavily-armored dinosaur.  Check out Anodontosaurus!

Anodontosaurus was an armored dinosaur in the ankylosaurid family that lived in what is now Western Canada, between 74 and 67 million years ago.  From snout to tail it measured about 20 feet long, and would have eaten plants when alive.  The genus name translates to "Toothless Lizard/Reptile" because it was originally thought to have been toothless. (but it wasn't). There are two named species within the genus.  The first discovered of the two was Anodontosaurus lambei, which lived later, while earlier-living species by a few million years was named Anodontosaurus inceptus. 

My life reconstruction of Anodontosaurus lambei in watercolors.  

Anodontosaurus, like most ankylosaurids was covered on the top side of its body with bony armor, called osteoderms.  These chunks of bone grew out from the skin, and many were keeled, and slightly triangular in shape.  Over its hips it possessed a sacral shield, a sheet of bone studded with osteoderms, growing over its hips.  Its skull was adorned with short broad horns above the eyes and lining the back of the head, as well as longer, broader horns growing out from under its eyes.  It had a wide beak at the front of the mouth and its jaws were lined with small teeth ideal for processing plants.  At the time of its discovery, however, because the skull as crushed in such a way after the animal's death, causing the teeth to fall out, scientists initially believed it was toothless in life.

After its initial discovery and naming Anodontosaurus was later lumped into the genus with another ankylosaurid relative, Euoplocephalus, thus losing its genus name.  However, in 2010, it was re-examined more closely and once again deemed different enough for its own genus, in a study led by paleontologist, Victoria Arbour.  The main reasons why the genus was split was because Anodontosaurus' horn arrangement, neck armor, and tail club were different from those of Euoplocephalus, and a few other ankylosaurids, which were also given their own genus from the study.  Anodontosaurus' tail club was unique in that it was elongated and pointed on either end, while Eouplocephalus' club is a smoother oval shape.

Cast of Anodontosaurus tail club on display at the American Museum of Natural History in New York.

Like all ankylosaurids, Anodontosaurus would have relied on its armor and tail club, which could be swung from side to side very powerfully, for defense against predators, like tyrannosaurids.  It is also very possible that ankylosaurids engaged in combat within the species, possibly smashing each other with their clubs, as well.  Anodontosaurus' tail club looks particularly wicked, since it comes to a point on either side, concentrating all the force onto a smaller surface when swung.  I'd imagine getting hit by Anodontosaurus would be more like being pummeled with a hammer than a club.  Ouch.

References

Arbour, Victoria (2010). "A Cretaceous armoury: Multiple ankylosaurid taxa in the Late Cretaceous of Alberta, Canada and Montana, USA". Journal of Vertebrate Paleontology. 30(Supplement 2): 55A.

Arbour, V. M.; Currie, P. J. (2015). "Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs". Journal of Systematic Palaeontology. 14 (5): 1–60.

C. M. Sternberg (1929) "A toothless armoured dinosaur from the Upper Cretaceous of Alberta." Canada Department of Mines Geological Survey Bulletin (Geological Series)54(49):28-33

Coombs, W.P., Jr. (1986, June). A Juvenile ankylosaur referable to the genus euoplocephalus (reptilia, ornithischia). Journal of Vertebrate Paleontology, 6(2), 162-173.

Penkalski, P. (2013). "A new ankylosaurid from the late Cretaceous Two Medicine Formation of Montana, USA". Acta Palaeontologica Polonica.

Spinosaurus: Beast of the Week

Make way (lots of room...back up more...keep going...keep going...backbackbackback) for the mighty Spinosaurus Aegyptiacus!

Spinosaurus was a meat-eating dinosaur that lived in what is now Africa, including Egypt and Morocco, during the late Cretaceous Period, about 97 million years ago.  It was a massive animal, measuring about forty nine feet long from snout to tail as an adult, making it the largest meat-eating dinosaur known to science.  The genus name, Spinosaurus, translates to "Spined lizard/reptile" in reference to the extremely long neural arches on it's back vertebrae. (We have neural arches too, just smaller.  If you run your finger down your spine, you can feel them.) Some of these spines were almost six feet tall, giving the animal a very striking profile in life.

Life reconstruction of a Spinosaurus aegyptiacus ambush hunting a crocodile while underwater by Christopher DiPiazza.

Spinosaurus has one of the richest histories behind its discovery.  It was first unearthed back in 1912 and published in 1915 by German Paleontologist, Ernst Stromer.  Back then all he had to work with was very fragmented remains including a part of a lower jaw, some vertebrae, and a few ribs, not enough to know for sure what the whole animal looked like, but certainly enough to tell it was something new and exciting.  For decades the remains of Spinosaurus remained in a museum in Munich, Germany, on display.  During World War II, allied forces bombed the area where this museum was.  Luckily some small fossils, including the first discovered Pterodactylus, and arguably the most valuable fossil in the world, Archaeopteryx, were able to be evacuated ahead of time but the poor bones of Spinosaurus were destroyed.  For decades the world had no real Spinosaurus fossils to study beyond the photographs and drawings left behind of the originals and small bits and pieces that didn't give any real new information found here and there every so often.  In fact, Spinosaurus teeth are actually quite common and are frequently sold in fossil and mineral stores.

Illustration of the original fossils found of Spinosaurus from Ernst Stromer's 1915 publication.  You can see three of the vertebrae with the tall neural arches on the left and the lower jaw piece on the lower right.  The straight, cone-shaped teeth are illustrated larger above the jaw.

It wasn't until the year 2005 that another big piece of Spinosaurus was found.  Italian Scientists digging in Morocco found pieces of a Spinosaurus skull, including most of the snout and the nostrils.  This showed that Spinosaurus had a much narrower snout than previously thought.  Then, this past year in 2014, paleontologist, Nizar Ibrahim, published a paper about even more material from this amazing animal, which included more of the spine and the hind legs that he and his team had uncovered in Morocco.  It was this discovery that changed Spinosaurus' image from unique to something that looks more at home in mythology. (Yes, even by dinosaur standards.)

Spinosaurus had many unique features about it that pretty much break all the rules of what we thought we knew about theropod dinosaurs.  We will start with the head and work our way back.  Spinosaurus belongs to a family of dinosaurs called spinosauridae (named after it, the first known member) which are all characterized by having very long, narrow snouts.  Their snouts are often compared to those of modern crocodiles, but this is mostly a superficial resemblance since they aren't mechanically that similar.  Spinosaurids all had straight, pointed teeth, and their nostrils were not at the tip of the snout, but higher up towards the middle.  These characteristics led scientists to believe that spinosaurids were adapted to hunting fish.  Their arms were powerful and possessed three fingers on each hand.  Digit one of each hand had an enormous, hooked claw on it, much larger than the other two.  This was probably another adaptation to hunting since hook-shaped weapons are common adaptations in predatory animals.

Spinosaurus skeletal mount on display at the National Geographic Museum.

As stated before, Spinosaurus had extremely long neural arches on its back that ould have been covered in skin and other living tissue when the dinosaur was alive, giving it a sail-like appearance in life.  This is not completely unlike the sail of the also famous mammal-like reptile (and totally not a dinosaur), Dimetrodon, which lived millions of years earlier.  Despite the similarities, these two animals are not directly related to each other and is just another beautiful example of convergent evolution.  The function of the sail on Spinosaurus is something nobody can quite agree on.  There are always those who will say an adaptation like that was for display within the species.  Others believe it was to help regulate the animal's body temperature, having possibly been rich in blood vessels in life and easier to heat up in the sun.  This is a good hypothesis especially if Spinosaurus was spending a lot of its time near or in the water to hunt.  Bodies of water always cool an area down and being in or near it can lower an animal's body temperature to the point where it needs to leave the area to warm up again.  Those that don't leave the water have special adaptations to help them stay warmer longer.  Think about ducks and geese (which produce their own heat, being endothermic) and how they have a layer down feathers against their bodies.  Also think about modern Marine Iguanas (cannot produce their own body heat as ectothermic) and how they can only stay in the ocean for a few minutes at a time until they need to haul out on shore to absorb more warmth from the sun.  A good way to experience this is going out on a boat during the summer, it may be hot on the land but trust me, you will want to bring a jacket if you are out on the water for a long while!  The sail on Spinosaurus may have been a way for it to increase its surface area to warm itself up in the sun as efficiently as possibly while still being able to hang out in places with lots of water for long periods of time.  The shape of Spinosaurus' sail has changed over the years with new discoveries.  The newest information about it suggests the sail was somewhat rectangular, with a shallow dip in the middle.

For decades, everyone just assumed Spinosaurus' legs were the same as those of its close relatives like Suchomimus and Baryonyx, fellow spinosaurids which scientists had more complete skeletons of and were typical for theropods, long and powerful, supporting an obligatory bipedal posture.  A discovery that was published in 2014 changed all that, however.  According to what was unearthed,  Spinosaurus had short legs...like really short legs.  So short that it would have had a rough time even standing on two legs.  For a while some people proposed Spinosaurus may have been a quadroped, possibly walking on its knuckles to keep its claws sharp, making it the only known quadrupedal theropod known in history.  (This idea is now mostly accepted as very unlikely, and Spinosaurus was probably still an obligatory biped, it just wasn't very graceful.)  Right after this publication was released many people thought that perhaps the paleontologists suggesting these odd proportions had not considered maybe their new leg material was from a juvenile specimen and was not scaled up to the other already-known material which was from adults.  The problem with that argument is that the new leg material was found with other bones that were almost certainly all from the same individual, including some of the long spine vertebrae, which were big just like the other adult-sized material already on the fossil record from Spinosaurus.  The mighty Spinosaurus really did have the proportions close to that of a dachshund mythical Asian Dragon!

Despite its proportionally small legs, assuming its front limbs were similarly built to those of any other theropod's, Spinosaurus still almost certainly only walked on its hind legs.  It was likely slower and clumsy on land, possibly dragging its tail for extra support.

The 2014 discoveries didn't end there.  Spinosaurus' feet were unique in that the toes were flatter and wider than what is typically seen in theropod dinosaurs, except for certain birds that have webbed toes for paddling like penguins and ducks, suggesting Spinosaurus had webbed toes as well.   Spinosaurus' bones were also not hollow like those of most other theropods.  Instead they were dense and solid.  Penguins are another kind of theropod with solid bones so that they can swim under water more easily.  These two amazing discoveries, combined with what we already knew about Spinosaurus' snout and teeth, lead us to believe that this dinosaur was specially adapted for a life in the water.  Even having short legs makes more sense.  Think of the legs of hippos and otters.  These are animals that, although capable getting around on land, really move best when under the water.  Also, if Spinosaurus was under the water a lot, having a large sail on its back which may have been more often poking above the surface to soak up some warmth from the sun, it would have been able to help prevent its body from getting too cold.  All of these strange adaptations which confused scientists for many years all start to come together a little more with the help of just a few more new (yet strange) discoveries!

The most recent discovery about Spinosaurus' anatomy was published in 2020.  Turns out Spinosaurus had a unique tail, as well.  The neural arches and chevrons (bony protrusions on the top and bottom of the vertebra) on the tail bones were greatly extended, implying Spinosaurus had a broad, paddle-shaped tail, like a gigantic newt! This actually makes sense since by this point scientists already had reason to think Spinosaurus was spending most of its time in the water.  This tail would have only helped Spinosaurus to move around in its environment.

Photograph of Spinosaurus' newly published tail bones from Ibrahim's 2020 paper.

Finally, if Spinosaurus was an aquatic dinosaur, it would also make more sense of what we know about its environment.  The areas that Spinosaurus bones have been discovered in have a lot of other fossils in them too, most notably lots of other species of meat-eating dinosaur, and also lots of aquatic creatures like fish, turtles, and crocodiles.  Before this year, it was assumed that Spinosaurus was so large because it was competing with other predatory dinosaurs, like the slightly smaller allosauroid, called Carcharadontosaurus, and various ceratosaurs.  Despite this, it still always seemed strange to have that many predators but not so many plant-eating dinosaurs in the community.  Now we know that Spinosaurus probably evolved in a completely different direction to avoid competition altogether.  It was more likely an aquatic predator, spending more of its time in the water hunting fish and other aquatic prey.  This way it wasn't occupying the same space, nor was it competing for the same food as its fellow theropods.  Since it was the only dinosaur to exploit such a unique niche, it could have evolved to be extremely large without any competition.

Spinosaurus running under the water like a boss...or a hippo.  I have my doubts if this dinosaur was actually good at swimming, through the water like a crocodile, but walking/running around under it, sure, given its anatomy.

Spinosaurus holds many titles as a dinosaur.  Not only was it the longest known meat-eater, it was also the only known non-avian dinosaur to have actually been aquatic.  This long-snouted, short-legged, webbed-footed, sail-backed, paddle-tailed beastie would have truly been a sight to behold!

References

dal Sasso, C.; Maganuco, S.; Buffetaut, E.; Mendez, M.A. (2005). "New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities". Journal of Vertebrate Paleontology 25 (4): 888–896. 

Ibrahim, N.; Sereno, P. C.; Dal Sasso, C.; Maganuco, S.; Fabbri, M.; Martill, D. M.; Zouhri, S.; Myhrvold, N.; Iurino, D. A. (2014). "Semiaquatic adaptations in a giant predatory dinosaur". Science.

Ibrahim, Nizar; Maganuco, Simone; Dal Sasso, Cristiano; Fabbri, Matteo; Auditore, Marco; Bindellini, Gabriele; Martill, David M.; Zouhri, Samir; Mattarelli, Diego A.; Unwin, David M.; Wiemann, Jasmina (2020). "Tail-propelled aquatic locomotion in a theropod dinosaur". Nature. 581: 1–4. 

Smith, J.B.; Lamanna, M.C.; Mayr, H.; and Lacovara, K.J. (2006). "New information regarding the holotype of Spinosaurus aegyptiacus Stromer, 1915". Journal of Paleontology 80 (2): 400–406. 

Stromer, E. (1915). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec". Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Mathematisch-physikalische Klasse (in German) 28 (3): 1–32.

Stellasaurus: Beast of the Week

This week we'll be checking out a newly described ceratopsian dinosaur.  Say hello to Stellasaurus anchellae!  Stellasaurus lived in what is now Montana, USA, during the late Cretaceous period, about 75.2 million years ago.  From beak to tail it measured about 20 feet long and would have eaten plants when alive.  The genus name, Stellasaurus, translates to "Star Lizard" due to its flamboyant horn ornamentation and in honor of the late rockstar, David Bowie, and his song, "Starman".

My life reconstruction of Stellasaurus done in watercolors.  Ziggy Stardust-style facial markings and body stripes may have been an adaptation to communicate with members of its own species.  (Nature has produced weirder things.)

Stellasaurus is characterized by having a massive nose horn that curved backwards, towards the tail end of the animal, much like the horn of a modern rhinoceros.  Stellasaurus' nose horn was also slightly laterally compressed, like a blade, rather than having a more rounded cross-section, which is unusual for ceratopsians.  Finally, this dinosaur sported two long, upwards-facing horns on either side of its frill.  The evolutionary purpose of these horns was likely for some sort of intraspecies communication, likely display and/or combat with rivals.  Because there is just so much variation in headgear amongst ceratopsian species, it is unlikely they were purely for defense against predators.  Stellasaurus was a member of the centrosaurine group of ceratopsians, which are characterized by their deeper snouts and proportionally smaller neck frills.

Right and left views of Stellasaurus' massive rhinoseros-like nose horn. (image from Wilson's 2020 paper linked below)

There are a lot of ceratopsian taxa on the fossil record.  New members of this wildly successful group of dinosaurs are being published every year.  That being said, Stellsasaurus is a particularly important find because it appears to help show an actual evolutionary line in action.  We know evolution is an ongoing process of older forms of organisms changing over time into newer forms in response to environmental changes.  That being said, it isn't common to be able to say with certainty one taxa was a direct ancestor or descendent of another in the fossil record.  However, looking at the frill horns of Stellasaurus, and then comparing them to the frill horns of other ceratopsians that lived in the same place as it from different times, paleontologists were able to see a likely linear transition between at least five different kinds of ceratopsians!

Left and right sides of Stellasaurus' frill and frill horns.  Note how it has two growing from each side.  (Image from Wilson's 2020 paper linked below.)

A close relative of Stellasaurus, Styracosaurus, which lived slightly earlier than Stellasaurus, had similar frill horns, but they were more numerous, with three on each side instead of Stellasaurus' two.  Einiosaurus, which lived a bit after Stellasarus, only had one of these frill horns on each side.  The even younger Achelousaurus, also had two horns on its frill, but they angled slightly outwards.  Finally, the youngest piece to the puzzle, Pachyrhinosaurus, also had these horns, but they were even more dramatically curved outwards.  The only thing that may not seem to match up is the difference in nose ornamentation between Stellasaurus' backwards curving horn, and Einiosaurus' extremely forward-facing horn, but keep in mind there were millions of generations of dinosaurs between these individuals, and therefore many more transitional forms that existed there.  Maybe we'll find yet another ceratopsian to fit into this line to make it even more detailed!

Stellasaurus provides a crucial puzzle piece in showing a possible direct transitional line among several different taxa of centrosaurine ceratopsians.

That is all for this week.  As always please leave your thoughts below!

References

Wilson, John P.; Ryan, Michael J.; Evans, David C. (2020). "A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the 'Styracosaurus-line' dinosaurs". Royal Society Open Publishing. 7 (4).

Bird Feeders: Sharing Our Earth with Wildlife

This Earth Day I want to focus on birds.  Birds are by far the most successful vertebrates on land today.  They outnumber all other vertebrates, including us, mammals, in terms of species diversity, as well as in sheer numbers.  With this in mind, paired with the fact that birds are dinosaurs, you could say the "age of dinosaurs" people often think ended millions of years ago, is still going stronger than ever.  A great way to see a wider variety of live dinosaurs without even leaving your home is by setting up a bird feeder.  Feeders come in a variety of sizes and types and can be set up even on windows of small apartments if need be.  I put together a list of thoughts to remember that I hope will help you get the most out of your bird feeder.

A Tufted Titmouse (left) and female Downy Woodpecker (right) sharing a meal at our feeder.  

Tip 1: Feeding wildlife is dangerous.

First off, I want to make it clear that most of the time it is an absolutely terrible idea to feed wildlife.  Normally when this happens, wild animals learn to associate humans with food, and therefore will start seeking humans out instead of foraging for food, themselves, like they naturally would be.  This is how you get what are referred to as "problem animals", like deer, bears, or even alligators, that lose all fear of humans and start living way to close to people for comfort.  Sadly these animals are often humanely killed by local authorities because they start posing a threat to people.  In addition to this, well-meaning people often feed wildlife inappropriate foods that don't meet the animal's nutritional needs, and in some cases actively hurt the animals.  Feeding bread to ducks, for instance, is actually detrimental to the ducks since they can't digest it and it can lead to developmental problems.

Snow White was super inappropriate when it came to interacting with wildlife.  Don't be like Snow White. 

Tip 2: Wildlife Still Needs Our Help.  It just needs to be given the right way.

Hold on...I started by saying I was going to tell you how to set up a bird feeder...but then said feeding wildlife is bad?  Which is it!?  Let me explain.  Bird feeders are a little different from blatantly throwing food at animals outside since in the case of bird feeders, the wildlife never associates the food with humans.  As far as the birds know you and the food you put out are completely unrelated.  This fact, paired with the assumption that the quality of food you're providing the birds is appropriate and adds to, not replaces, their wild diet (which we will cover below), results in a totally safe scenario for all parties, with some added food available for the birds, and entertainment for you!  I'm a firm supporter of the idea that wildlife should stay wild.  However, I also completely support the idea of humans actively helping protect and preserve wildlife when it's needed and if it's done appropriately.  Wild bird numbers have been consistently dropping at an alarming rate and it's absolutely in response to human activity, predominantly pollution, habitat destruction, and climate change.  So putting a bird feeder out is a small way to maybe help some wild birds get some extra energy and nourishment in their already stressful daily lives living in the wild.

Tip 3: The variety of animals present is entirely dependent on the habitat available.

In order for wildlife to be present there must be a habitat.  It sounds like a no-brainer, but it's important to keep in mind. The kinds of birds that will come to your feeder will depend on the kind of habitat you are currently near.  That being said keep in mind that urban areas with lots of human development are absolutely habitats for wildlife, too.  I have seen lots of really interesting species that make their homes in highly populated cities.  If you do live on a property where you have a yard and the ability to control the kinds of plants and landscaping that's present, you can change the habitat and possibly attract more species over time.

Habitats are less restricted by space than you think.  This is important especially if you live in a small home with no yard, or in an apartment.  This doesn't mean you can't still provide at least a small change to make your home a little better for wildlife.  Many flowers and other native plants do just fine in potted plants that can exist on windowsills.  Bird feeders that attach directly to windows via suction cups are easy to find and purchase.  My point is no matter what kind of home you live in, attracting more wildlife is always possible.

Eastern Bluebirds only nest in meadows and fields, so if you don't have a space like that nearby, you are unlikely to see them very often.  I took this photo miles away from my house because I don't have the right habitat near my property for this species.

Tip 4: Insect protein is essential for nutritious bird feeders.

The more variety in food is in your feeder, the more variety in wildlife you'll attract.  Lots of people simply buy a bag of seeds to fill their feeders.  If you really want to attract more species of birds, as well as provide them with more useful nutrients, make sure your bird feeders have insects in them!  Keep in mind that in the wild, many songbirds eat a lot of insects.  In fact, songbirds, even the ones that are often associated with eating seeds and fruit, are one of the strongest forces that control insect populations in the world, alongside bats and amphibians.  Luckily any garden store, or other place that already sells wild bird seed, will have bags of dried mealworms that you can mix into your feeder.  Some bird feed companies also make bags that include both seeds and insects together.

Downy Woodpeckers, like all woodpeckers, eat insects year round.  A suet block, like the one this male is feeding from, is essentially a powerbar for birds, loaded with protein from both ground nuts and insects.  

Tip 5: You don't need to hate on squirrels so much.

I see people often complaining that they get too many squirrels eating out of their bird feeders. I've even witnessed many people state they actively avoid setting up bird feeders because they're so turned off by the squirrels.  Where I live we have Eastern Gray Squirrels.  They're extremely common, but they're still native, and therefore a part of the natural environment.  They help plant trees by burying seeds and nuts (and forgetting to retrieve them) as well as provide a valuable food source for many charismatic predators, like hawks and owls.  In addition, even though it may seem like squirrels are hogging all the bird seed, I assure you the birds are still getting meals out of the feeder.  That being said if you still want to reduce the frequency of squirrel feeding and increase that of birds, many bird feeders have mechanisms that (somewhat) deter squirrels built into them, like perches that collapse under the weight of a squirrel, but not a bird.  You can also buy bird seed that has hot peppers in it which squirrels don't like, but birds do.  That's right.  birds have different taste receptors from mammals, including the inability to register capsaicin, the chemical that makes you feel like your mouth is on fire when you eat spicy food.  (When I was a zookeeper the cockatoos LOVED to snack on chili peppers.)

The neighborhood we live in has a high concentration of melanistic Eastern Gray Squirrels.  Melanism is when an animal is born with more melanin, the pigment that makes skin and hair darker.  

Tip 6: Clean your bird feeder between fillings.

When your bird feeder is empty, scrub it thoroughly with soap and water and let it air dry for a day before you fill it up again.  Old food residue will start to harbor bacteria and fungus that will make birds sick when they use the feeder.  Not letting the feeder dry all the way before filling will also grow fungus that can be harmful to birds.  Same goes for hummingbird feeders.

This is a male and female Eastern Goldfinch that visits our feeder almost every day.  This photo was taken in early March, and you can see the male wasn't quite shedding away all of his brown winter feathers for his bright yellow mating season feathers.  The female, although more drab than the male, also turns more yellow in the warmer months. 

Tip 7: Don't be surprised if your bird feeder becomes a bird feeder... feeder.

By this I mean that if you have songbirds visiting your feeder enough, their predators will start to hang around too for obvious reasons.  Since putting up my feeder this past winter, I see the local Coopers Hawk and a young Red-Shouldered Hawk showing up more often.  As with the squirrels, some people don't like birds of prey at their feeders because they feel bad for the pretty songbirds that are at the feeder.  In my opinion it is important to keep in mind that regardless how cute these little birds are, they are still an active piece in the local ecosystem, and being food for a predator is an inevitable and necessary fate for some of them.  After all, the predators need to eat too.

Predators of songbirds, like the Barred Owl I photographed in October, are a necessary part of any ecosystem.  Owls especially also heavily control rodent populations.

Tip 8: KEEP YOUR CATS INDOORS!!!

There is literally no positive aspect of having an outdoor cat.  None.  Not for the cat, and certainly not for any wild animals that now have to share space with the cat.  A recent scientific study came out that proves just how many birds and other native animals domestic cats really kill and the numbers are horrifying.  It's estimated that domestic cats are responsible for the deaths of BILLIONS of wild birds per year.  Billions.  With a B.  That's more bird deaths than by window collisions!  Some might argue that an outdoor cat is simply part of the environment and doing its part as a predator.  This opinion is extremely wrong for a few reasons.  First of all, domestic cats are originally native to Northern Africa, from where they spread to there rest of the globe with humans as pets, and therefore have no business in most ecosystems where they're killing birds.  So this is why outdoor cats are such a problem, but the birds of prey that also kill small birds I previously mentioned, are not.  Second, even if you were to try to reason that cats are taking the place of other predators that previously lived in these areas before humans developed over them, like bobcats, you'd still be wrong.  This is because one bobcat can have a territory that stretches for several miles which they will defend from other bobcats violently.  Plus, although Bobcats do eat birds naturally, they don't kill them nearly as frequently as one domestic cat does.  Domestic cats also aren't nearly as territorial so many individuals can be roaming the same small space, and since they're often being fed by their humans anyway, they're killing birds out of instinct/play, not to survive.  Another important point is that being outdoors unsupervised is extremely dangerous for the cat, as well.  Typical lifespans of cats that are allowed to roam outdoors are significantly shorter than those of cats that stay indoors.  They're exposed to parasites, fleas, all sorts of diseases, and of course are at risk of being killed by cars and even wild predators, like coyotes and even large birds of prey.  If you're a cat owner like me, you can keep your cat perfectly happy indoors with toys and plenty of attention in the form of play sessions with you, the owner.  You can also totally get your cat used to a leash for outdoor adventures that is safe for both the cat and the local wildlife.

One of our cats, Beaker, wasn't a fan of the leash at first, but now she loves her (wildlife-safe) outdoor adventures.

Tip 9: Citizen Science is fun.

Citizen science is when amateurs or non-professionals participate and contribute to scientific research.  This can take lots of forms, like volunteering at your local nature center to help gather data on local wildlife populations.  However, some citizen science can be done without even leaving your house, like something as simple as counting the number of birds that visit your feeder.  Free apps like ebird and iNaturalist allow you to document bird numbers and species as you see them, and scientists can use that data for their research.  Not able to identify every bird that you see?  No problem!  Both these apps have features that actually help you identify mystery animals in real time, so you're learning to identify local wildlife you share your home with, too.  It's also fun to rack up as many bird species as possible and compare to other folks doing the same thing in their homes!

Northern Cardinals, like this female who visited our feeder yesterday, use their powerful beaks to crack open shells of nuts.

I hope this list of tips helped inspire you to start your own bird feeder.  If you already have a feeder I'd love to know what kind of visitors you're getting.  I personally have spotted a total of 28 species at my feeder since setting up this past winter.  Share your species count or the coolest bird you've seen on your property in the comments below!

Pterodaustro: Beast of the Week

This week we will be taking a look at a bizarre pterosaur.  Let's check out Pterodaustro gulnazui!

Pterodaustro was a pterosaur that lived in what is now Argentina, during the Cretaceous, about 105 million years ago.  Adults had a wingspan between eight and nine feet long and they would have likely eaten meat in the form of very small animals (more on that in a bit).  The genus name translates to "Wing from the South" and the species name honors paleontologist, Roman Gulnazu.

Pterodaustro life reconstruction I produced in watercolors.  Because this creature was likely a filter feeder it is often restored with pink coloration, like a modern flamingo, but many other animals that filter feed, like ducks, do not become this color and there is no reason to think Pterodaustro was more likely pink than not.  

Pterodaustro is a well-studied pterosaur.  It is known from multiple complete skeletons, including adults, juveniles, and even eggs with embryos still inside.   Thanks to this array of specimens paleontologists know a lot about this strange creature's life appearance and growth pattern.  

 By far the most striking feature about Pterodaustro is its face, particularly its mouth.  This pterosaur sported a long, thin beaklike mouth that gently curved upwards.  Growing up from the lower jaws were over a thousand bristle-like structures.  These structures, although hair-like, were actually highly specialized teeth.  It is thought that Pterodaustro used these modified teeth for filter feeding tiny creatures out of the water, much like a modern flamingo, or some whales do with baleen.  Pterodaustro also had very small, teeth on the upper jaws, possibly for processing its food after trapping it in the mouth with its unusual lower teeth.  A few Pterodaustro skeletons were found to have tiny rocks in their stomach cavities.  Many reptiles, including dinosaurs, lizards, and even modern birds, are known to swallow tiny rocks, called gastroliths, which help aid in crushing up food inside the stomach or crop once eaten.  Pterodaustro is the first example of a pterosaur that also did this.  Because of these rocks, it is implied that the food Pterodauestro was eating wasn't soft, so it was probably specifically filtering tiny crustaceans that sported exoskeletons that needed to be crushed and broken after capture.

Pterodaustro skeletal cast on display at the Museo Argentina de Ciencias Naturales in Burinos Aires, Argentina.

Pterodaustro had a long, thin neck and a relatively long torso for a pterosaur.  Its hind legs were proportionally short so it may not have been a very fast walker.  In order to get into the air to fly, takeoff also would have been relatively difficult because its short legs would have hindered it from launching very far from the ground.

The Pterodustro eggs on the fossil record are similar to other known pterosaur eggs in that they would have had somewhat soft shells, more similar to those of modern turtles than birds.  The babies would have only been a few inches long when first hatched and would have grown very quickly for their first two years of life until they became sexually mature.  They would have continued to grow at a slower pace for four to five more years.

That is all for this week!  As always please leave a comment below!

References

Chinsamy, A., Codorniú, L., and Chiappe, L. M. (2008). "Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui". Biology Letters. 4 (3): 282–285.

Codorniú, L., Chiappe, L.M., Arcucci, A., and Ortiz-Suarez, A. (2009). "First occurrence of gastroliths in Pterosauria (Early Cretaceous, Argentina)". XXIV Jornadas Argentinas de Paleontología de Vertebrados

John D. Currey (1999). "The design of mineralised hard tissues for their mechanical functions". Journal of Experimental Biology. 202 (23): 3285–3294.
Witton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.