Saucebacks' placement among binucleids is as follows:
The general phylogeny of saucebacks, with additional species for context, is shown here.
†: Taxon is extinct
AnatomySaucebacks are bipedal, and all extant saucebacks have feathers. Though many appear to have a neck, this is technically a proboscis--the carapace on the back, also known as the "sauce", is also the top of the braincase and therefore part of the head (see cephalic segment).
The inside of a sauceback's mouth, known as the oral ring, is lined with teeth, the largest pair of which--the "tusks"--being mobile and serving as jaws. Inside the oral ring are the teeth which line the inside of the mouth, which are also mobile and are used in mastication. The number of teeth a sauceback has, including its tusks, directly corresponds to the number of nostrils it has, as the two are directly tied in development. The teeth and nostrils are also developmentally tied to the scent line, similar to a mammal's milk line. The scent line encircles the oral ring. It isn't necessarily a straight line, but you'll always be able to draw an invisible line to connect all the nostrils without crossing over itself.Saucebacks have lungs in their tails which serve for active respiration. They breathe out of four or five pairs of spiracles on their tail or back, which may be located close to the sauce or much further back. The nostrils are not used for breathing, instead merely being scent pits which are not connected to the lungs. Though the first four or five postpelvic vertebral segments, consisting of the relatively large pulmonary vertebrae and the respiratory system, are commonly referred to as part of the tail, technically speaking the tail only consists of the much smaller and more flexible segments after these, which also aren't present in all saucebacks.
The legs of modern saucebacks, apart from the biats, are pillar-erect, meaning that rather than fitting diagonally into a closed socket on the side of the pelvis like the legs of mammals or dinosaurs, the entire limb is anatomically like a pillar holding up the body, via a structure called the "architrabis" protruding from the pelvis (not to be confused with the acetabulum, which is actually a rigid joint connecting the ischium to the rest of the pelvis but serves as the hip socket in murkworms and in extinct non-dromeodont saucebacks). In biats, the head of the femur bends to fit into a closed socket instead as an adaptation for flight. In all descendants of the tusked sauceback, part of the hip girdle is formed from an internalized limb segment. In living species, the limbs are biramous--that is, they branch, forming a cloven hoof instead of the single hoof ancestral to the group.
Saucebacks have two types of vertebrae which evolved completely independently of one another. The tail vertebrae exist in all beastworms. The neck vertebrae are not homologous with these, having developed to hold up the previously soft tissue-based neck-proboscis.
Saucebacks will sometimes appear to have larger heads than they "should"--that is, proportionally larger than the head of a terran vertebrate in a similar ecological niche. This is due to the shape of their skull--as it consists of a rigid ring, saucebacks can only swallow food that fits through it, and as they can't expand it and their ability to chew is limited, having a larger head is the simplest solution. The exception is latrotheriid waxfaces, which are able to expand their skulls to swallow large prey.
Skeleton of a modern sauceback. Artwork by Evolution.
Musculature. Artwork by Evolution.
Though commonly colored white in diagrams for visual clarity, sauceback bones are actually black due to sclerotin, which gives them their hardness.
Full Skeleton Overview
Modern saucebacks have a number of bones.
- Cephalopelvis: A structure consisting of the sauce bone, the pubis, and the ischium. This serves as the pelvis and partially as a ribcage, as the pubis bows outwards to make room for organs. The brain is contained within the cephalopelvis, right at the front near where it meets the neck.
- Pubis: Provides muscle attachments for the legs which helps to hold them in a vertical posture.
- Ischium: Provides muscle attachment to pull the leg back while walking or running. It is technically an internalized first limb segment that has been fused to the cephalopelvis.
- Gastralia: Not technically part of the cephalopelvis, these serve to protect the abdomen, similar to ribs.
- Skelos: The collection of bones which make up the entire leg.
- Femur: Roughly analogous to a tetrapod's femur. It fits into an open ball socket joint above it on the cephalopelvis, rather than bending to slot into a hole, which is why non-biat saucebacks are described as having a pillar-erect posture.
- Tibia: Second segment of the leg, connected to the femur by the knee joint (which is a hinge). Some saucebacks also have a kneecap.
- Tarsus and metatarsus: The bones making up the "foot". The tarsus is connected to the tibia by a hinge, and the metatarsus is connected to the tarsus by a rigid (non-moving) joint called the "albert joint".
- Phalanges: These are the segments of the toes, connected to the metatarsus by a saddle and to one another by hinges.
- Ungual: The final phalange of each toe, connected by a hinge joint. The hoof is sheathed over this bone.
- Pulmonary vertebrae: These are the large segments which correspond directly to the microlungs. Most saucebacks have 4, some have 5. A pair of microlungs develops in each of these segments. Saucebacks rarely reduce their number, as fewer microlungs would mean less oxygen entering their bloodstream.
- Postpelvic gastralia: Attachment points for the muscles involved in breathing, they also help protect the lungs.
- Caudal vertebrae: Additional segments past the pulmonary vertebrae form the true tail, which is primarily used for balance. These may vary in number.
- Tail spike: In some saucebacks, this corresponds to an external sheath of chitin which protects the tail tip.
- Cervical vertebrae: Provide support for the neck. They may vary in number.
- Oral ring / skull: Contains the teeth and provides muscular support for the mandibles.
- Teeth: Aid in shredding food as it enters the mouth, these can wiggle back and forth. They may vary in number.
- Mandibles: Enlarged teeth used for biting, function as the jaws. These open and close side-to-side and have some up-and-down motion which varies between species.
Saucebacks do not have tetrapod-like anatomy, so they have a different set of locations that can be targeted by predators or by prey defending themselves.
- Chest: Unlike tetrapods, saucebacks have their digestive system on the front end of their body cavity.
- A sufficiently powerful strike to a sauceback's chest can potentially rupture its intestines.
- A slicing attack, if it gets through their gastralia, is guaranteed to disembowel.
- Tail: The first few segments from the base of the tail contain the sauceback's entire respiratory system.
- A strike to the base of the tail or suddenly yanking the tail sideways can knock the wind out of a sauceback, as the lungs are contained within.
- If the spine is broken at the base of the tail, the sauceback's lungs will be paralyzed and it will suffocate.
- Neck: Saucebacks do not automatically die from a broken neck, however it is nonetheless still a weak point for different reasons.
- Breaking the neck will instantly blind the sauceback, as its ears or eyes no longer have communication with its brain. The mouth may still involuntarily flex and bite and respond to visual information, but it will lack proper direction from the brain.
- Hip/Back: The sauceback's brain is contained within the hip girdle.
- A strike to the sauce plate (above the legs in plateless species) can stun or cause a concussion.
- Legs: Saucebacks are obligate bipeds. Breaking a leg is a death sentence in larger species unless they have a pack to take care of them.
As a very diverse group which has claimed a myriad of disparate niches in both past and present, saucebacks are highly variable in behavior, ranging from highly social to strictly solitary, from active and persistent to sluggish and lazy, and from clever and innovative to dumb as rocks.
Saucebacks have historically been fairly intelligent among Sagan 4's fauna, though like many other groups, they seemingly never accomplished tool use worth mention until after the ice age. Among modern groups, waxfaces, loafshells, and harnessbacks seem to be the most intelligent, with the former two having species that exhibit tool use and the latter including a species that herds livestock.
Not all species can be described as smart, however. Shrewbacks in particular are often quite lacking in intelligence.
Breathing & Blood
Saucebacks breathe actively using 4 or 5 pairs of microlungs along the flank of the tail that are designed to take in oxygen. The ancestor of the saucebacks had pores all over the body. Saucebacks have an iron based blood, which makes it red.
Some saucebacks have developed unidirectional lungs through fusion of the microlungs. Such a system is beneficial to saucebacks with highly oxygen-demanding lifestyles, similar to the evolution of unidirectional lungs in Terran birds, monitor lizards, and grasshoppers. An example of a living sauceback with unidirectional lungs is the sausophrey, which has only two pairs of spiracles--one for inhaling and the other for exhaling.
Diet & EnergySaucebacks eat using a toothy radial mouth. Modern ones have tusk-like jaws in front of the tooth ring to grab their prey, but there used to be ones who had four jaws to bite. While saucebacks were ancestrally carnivorous hunters of large game, many modern species are omnivorous or even herbivorous.
Some saucebacks will consume large amounts of chitinous flora to help build their skeletons. However, this is not a requirement for all species.
As endotherms, exceptionally small saucebacks have fairly high metabolisms and must eat very often.
The saucebacks all evolved from the first sauceback, the golden sauceback. They quickly split into two lineages, vicious saucebacks (descended from the vicious sauceback) and what would eventually become modern saucebacks (descended from the leaping sauceback). At the time, Sagan 4 had two continents; vicious saucebacks lived on Glicker, while the ancestors of modern saucebacks lived on Wright.
In general, vicious saucebacks showed little diversity early on, while the ancestors of modern saucebacks diverged into many forms. The tusked sauceback, which elongated a pair of teeth and internalized its first limb segment, evolved in the Flischian period, and it gave rise to a handful of dead-end branches such as the twin-tailed saucebacks and aquatic swimming saucebacks. It also gave rise to the feathered sauceback--an active, warm-blooded species which would go on to produce many descendants.
When the gamma-ray burst occurred during the Martykian period, it wiped out all but two species, those being the falsequill sauceback and the long eared sauceback. The falsequill sauceback would produce a small number of descendants, mainly burrowing ambush predators, but diversity of its lineage continued to be fairly low. The long eared sauceback, on the other hand, continued its ancestral tend of diversification. One descendant, the cleaner sauceback, was the first sauceback with cloven hooves--and the last common ancestor of all modern saucebacks. The other immediate descendant, the dark sauceback, would give rise to the beach sauceback--the first sauceback to develop any form of photoreception.
When the ice comet struck in the Raptorian period, all remaining vicious saucebacks went extinct. However, the smaller feathered saucebacks continued to thrive. The beach sauceback would give rise to scorpion saucebacks and dagger saucebacks (descendants of scorpion sauceback and four dagger sauceback, respectively). Meanwhile, the cleaner sauceback and its descendants would go on to produce three major groups: polar saucebacks (descendants of snow sauceback), larvabacks (descendants of the false-larva sauceback), and waxfaces (descendants of the waxface). Larvabacks and waxfaces are more closely related to one another than to snow saucebacks, sharing a common ancestor--the foi-devourer sauceback. While snow saucebacks were simply basal cold-adapted saucebacks, the larvabacks are neotenous marine creatures while the waxfaces had internalized all their exposed carapace to protect them from chitinase.
When Sagan 4 entered its snowball event in the Bloodian period, only the snow saucebacks, waxfaces, scorpion saucebacks, and larvabacks would survive. Scorpion saucebacks notably went through a radiation of forms utilizing mimicry. However, scorpion saucebacks would go on to be wiped out by the solar flare that followed at the start of the Masonian period. Waxfaces saw a radiation on Jaydoh, where they were isolated, and they nearly became extinct due to rising sea levels; however, they were ultimately survived by the Pirate Waxface, which followed its prey out to sea. This leaves larvabacks, waxfaces, and snow saucebacks as the current living sauceback groups.
Meanwhile, snow saucebacks, survived by the glacial sauceback, had managed to become global during the snowball event and diverged into a huge variety of new forms all over the planet once the ice receded. In fact, it holds the current record for most immediate descendants of any species of sauceback. Among its immediate descendants, the Masonian period saw the rise of megatusk saucebacks (descendants of the megatusk sauceback), which have enlarged tusks and later beaked trunks; and loafshells (descended from the loafshell), which have a segmented carapace, venom, and tridactylism.
Later descendants into the Blargian period would produce more major groups, including harnessbacks (descendants of the harnessback), which have a more advanced respiratory system protected by enlarged back plates and even produced an eyed descendant; and Hagloxes (descendants of the haglox), which are very large muscular herbivores as well as the largest saucebacks to ever live.
Even more new groups would appear in the Bonoian period, such as shrewbacks (descendants of the Shrew Sauceback), which are very small and have high metabolisms like Terran shrews; and ornitheres (a subgroup of harnessbacks descended from brighteyes), maniraptor-like and sometimes flighted saucebacks with shining "eyestrils". From the latter, flighted bird-like ornitheres, dubbed "biats," diversified considerably throughout the late Bonoian and into the Huckian, rapidly establishing themselves in Sagan 4's ecosystem.
The vast majority of saucebacks are obligate bipeds, though a handful of species have evolved tripedalism using their tails as a third leg. Most living species walk on cloven hooves, and some are capable of flight using integumentary, bird-like wings.
The first saucebacks had no toes and their limbs were capped with a single hoof bearing cleat-like protrusions. The ancestors of modern saucebacks simplified this into a horse-like hoof, while the now-extinct vicious saucebacks elaborated the cleats into clawed toes. Technically, modern saucebacks have no toes either; rather, their limbs are biramous, meaning that the limb itself branched to form the cloven hoof.
The legs of living saucebacks would seem to resemble digitigrade or unguligrade dinosaur hindlimbs, but what's going on internally is quite different. Ancestral saucebacks had an additional limb segment that is not apparent in modern forms; this was internalized and modified beyond recognition to form the part of the hip girdle which projects and curves backwards to provide muscular support for the "femur". This segment was external and articulated in vicious saucebacks, which is what causes their limbs to appear "backwards" compared to modern saucebacks. Additionally, unlike dinosaurs, saucebacks have pillar-erect limbs--that is, instead of bending sideways to fit into a socket, the femur connects perpendicularly to a horizontal protrusion of the hip, acting quite literally like a pillar to hold up the body.
Diversity of sauceback locomotion:
Stride Sauceback, a typical bipedal cursorial sauceback
Sanashi, a tripedal sauceback which walked on its tail
Sausophrey, a flying sauceback
Kuraimingaku, an arboreal sauceback which uses its jaws and tail to help it climb
Dixon Finback, a secondarily aquatic sauceback which swims with a left-right undulation of its tail
Saucetea, an extinct secondarily aquatic sauceback which swam with an up-down undulation of its tail
Dune Sauceback, an extinct sauceback which had a sprawling posture and "swam" through sand dunes
Reproduction and Development
Most saucebacks are sexual reproducers, they have two sexes, and lay eggs. Some species have a larval form; ancestrally this resembles a grub and bears a complete exoskeleton, similar to ancestral thornworms, but more derived species have larvae which resemble legless, featherless adults. Several species have specialized their larvae for different lifestyles, and some have even lost the larval stage altogether, instead hatching as developed chicks. With no exception, sauceback larvae breathe air just like their parents, though a handful of species have aquatic larvae regardless. Some saucebacks are ovoviviparous.
The eggs of saucebacks are more similar to those of insects than to those of vertebrates. The earliest saucebacks had to lay their eggs somewhere moist, such as underground or in a carcass. However, somewhere along the way, the ancestors of modern saucebacks evolved a serosa, which secretes a chitinous desiccation-resistant cuticle, or shell, over the egg. While this was lost in the line leading up to larvabacks and waxfaces, it is present in most other saucebacks.
Saucebacks with larvae grow in a gradual metamorphosis, changing from larval form to adult form over time, and do not pupate. Even in species with precocial non-larval young, there can sometimes be considerable differences between juveniles and adults; for example, falcophrey chicks cannot fly and megalosheh chicks are bipedal. Some saucebacks, such as waxfaces, produce milk to feed their young.
Ancestrally, saucebacks' primary sense is echolocation. They usually have large ears. Most non-ornitherian saucebacks have a very strong sense of smell. They typically use this to seek out prey from long distances. To smell, they have moist olfactory pits or "nostrils" around the mouth.
Saucebacks almost universally lack eyes, though their ring of nostrils is commonly mistaken for them. There are exceptions, however, which have been sharply rising in prominence.
- The hearthead actually converted its nostrils into pinhole eyes by adding dark light-sensing pigments to the inside, making it the first species where the "nostrils" really are eyes.
- The Lipped Sauceback and the Kuraimingaku also evolved "eyestrils" independently of the hearthead. In both cases they only dedicated one or two pairs of their nostrils into visual information.
- A group of extinct saucebacks descended from the beach sauceback had an infrared-receptor on the forehead.
- The long extinct Sauceback Hunter had developed an organ on top of their heads that allowed them to detect the heat of prey that was close to them, but it poorly developed and only worked at close range.
Modern saucebacks cannot taste sugar.
Saucebacks have ranged from 9 m Long all the way down to 3 cm Long.
There are two extant classes of sauceback, the dromeodonts and the ornitheres. The dromeodonts are further divided into the neodromeodonts and the metaverms. The phylogeny of each major group is as follows:
*As is visible in this tree, ornitheres are technically well-nested within the neodromeodonts. They are classed separately due to their dramatic divergence in appearance and anatomy.
Loafshells (order Panemverma) are often venomous saucebacks descended from the loafshell with distinct downwards-pointing jaws and segmented, "loaf-like" shells. A spur on the back of the foot is elaborated into a third toe in some species.
Harnessbacks (order Placopulmonates) are descendants of the harnessback which have chitinous ceres around their spiracles which provide support for their lungs, granting them more stamina than other saucebacks.
Beaked saucebacks (Order Tateatama) are descendants of the Sanashi which, as their name implies, have massive jaws used like a mobile version of an elephant's tusks. Many species are also armored and have long mouths tipped with specialized teeth that function as beaks.
Shrewbacks (family Vermisoricidae) are descendants of the Shrew Sauceback which are small and, as adults, have high metabolisms, much like Terran shrews. Their ectothermic larvae are among the most independent of any living saucebacks.
Logworms (order Labiliverma) are saucebacks with fleeting adult stages, instead living most of their life as larvae.
Fourmaws (order Quattuorgnatha) are an offshoot of logworms which, peculiarly, regained a long-living adult form--and re-evolved jaws from scratch.
Outside of the neodromeodonts, there are the metaverms (subclass Metaverma), which all share an aquatic or aquatic-adapted larval form which bears hair-like snorkel structures and shelless eggs which must be kept moist, such as by being laid in water. While the neodromeodonts evolved aquatic larvae independently, only the Metaverma have the snorkels.
Waxfaces (order Cryptosagmatia) are saucebacks descended from the waxface which lack any external chitinous plates, even walking on padded feet instead of hooves. Their namesake feature is the production of wax which covers their faces and jaws, allowing them to feed on organisms which use chitinase as a defense. Living species also use their wax to waterproof their feathers.
The ornitheres are a visually distinct lineage descended from brighteyes which have evolved mirror eyes derived from their nostrils. In terms of cladistics, they are technically neodromeodonts, but are separated due to their specialized anatomy and lifestyle leaving them irreversibly unrecognizable as saucebacks. Some species are capable of flight. More information on their various subgroups can be found on their overview page.
Vicious saucebacks (class Hesperognatha), sometimes misleadingly referred to as jawed saucebacks, were basal ectothermic saucebacks descended from the Vicious Sauceback which had four jaws, as opposed to the two found in tusked saucebacks. They died out as a result of the ice comet impact event.
Scorpion saucebacks (family Scorpiotheridae) were single-hoofed saucebacks descended from the Scorpion Sauceback which evolved biramous limbs independently of true double-hoofed saucebacks. They killed prey with their tails, which were arched over their backs like the tail of a scorpion. They died out at the end of the snowball event.
Dagger saucebacks (family Mucronisagmatidae) were descendants of the Four Dagger Sauceback which used their jaws and extensions of their sauce plate as blades and impaled their prey on them to kill them. They died out as a result of the snowball event.
Two-tailed saucebacks (family Dicaudatheriidae) were basal tusked saucebacks descended from the Two-Tailed Sauceback which, as their name implied, had two tails. They were wiped out by the gamma ray burst.
The types shown here technically still have living descendants, but they have deviated so strongly from their extinct ancestors that they are no longer regarded as the same type.
Featherless Tusked Saucebacks
Single-Hoofed Feathered Saucebacks
The basal featherless tusked saucebacks (order Manioraliformes) descended from the Tusked Sauceback lacked the feather covering of their living descendants. These basal forms became extinct as a result of the gamma ray burst.
Single-hoofed feathered saucebacks (order Plumatheriformes) descended from the Feathered Sauceback lacked the biramous limbs of later groups. This basal grade became extinct at the end of the snowball event.
- For a time, Sauceback clones were very common in Spore-based worldbuilding projects.
- Saucebacks have been subject to a great amount of misinterpretation compared to other lineages.
- It is very common for the nostrils around the face to be misinterpreted as eyes. The "eyestrils" of the hearthead are a light-hearted reference to this phenomenon.
- As a result of a woefully inaccurate skeletal diagram being added to this very page, for a time it became extremely common for saucebacks to be misinterpreted as having completely toothless mouths apart from immobile tusks. Some extant branches, such as hagloxes, are still afflicted by the lingering effects of this misinterpretation.
- Beastworm: "the beastworm has developed an internal support structure made of the same material the old, very hard shells were."
- Krikrees#Anatomy: "Although the bones are colored white in these diagrams for clarity, the bones of krikrees--and all other saucebacks--are actually black, due to sclerotin."
- Sanashi: "Over time the tail evolved into a 3rd foot and now when walking they have a tripod walk."
- Just how are sauceback eggs, really? - thread on the Sagan 4 forum by Disgustedorite, posted on Jan 23 2021
- Falcophreys: "Quite unlike the birds of prey they resemble, their young are able to run soon after birth, allowing them to escape from predators, though they cannot yet fly."
- Megalosheh: "Young legged Megaloshehs are cursorial and bipedal, able to sprint deeper into the herd at any sign of danger"
- Hearthead: "The insides of its nostrils are lined with dark light-sensitive pigment, which allow it to detect light and shadow; in combination with the 3d shape of its nostrils and how many nostrils it has, this allows it to detect a blurry monochrome image so that it may navigate around obstacles and locate its babies without echolocating, as long as it is in daylight."
- Brighteyes: "As there was no way to develop a lens without closing off its scenting capability, it took a completely different approach to improving its eyesight. The back of each eyestril is reflective and directs the light towards a light-sensitive patch in the front, and direct stretching and squashing of the entire eyestril allows it to focus as though it were a lens."
- Lipped Sauceback: "It has also gained pinhole eyes derived from two of its scent pits, convergent with the unrelated Hearthead"
- Kuraimingaku: "In a similar manner to the lipped sauceback, the kuraimingaku evolved pinhole eyes from four of its scent pits."
- Beach Sauceback: ". It has also developed a simple, light-sensitive patch on it's forehead for hunting that detects light in the infrared range."
- Sauceback Hunter: "In order to get an advantage on its prey, it has begun to develop a very basic heat sensing organ on its forehead. Currently this organ is completely useless unless it's close to its prey, but that's enough for the organism to keep the enhancement and pass it on to further generations."
- Krikrees#Hunting_and_Foraging: "They cannot taste sugar, as like all modern saucebacks their ancestors had been hypercarnivores that lost that ability"