Sources and what was checked

The 3D shapes are stylized, not scanned from real animals. In October 2026 the placement of each part and the guidance text were compared with the references below. Most references are hunter-education and hunting publications; the veterinary references describe cattle, sheep and goats, which share the same body plan as deer and elk but are not identical. Treat everything here as a learning aid.

Confirmed matched a source as built. Corrected changed to match a source. Not verified no adequate source found.

Skeleton

• Confirmed7 neck, 13 chest and 6 loin vertebrae. Kumar et al., Anatomy of deer spine, The Anatomical Record (2000).
• Confirmed13 pairs of ribs, the first 8 joined to the breastbone. N.I.M.R.O.D.S. whitetail anatomy guide (a hunting site, not a primary reference).
• CorrectedRibs re-spaced so there is one per chest vertebra, with the chest vertebrae ending about halfway along the body and the front ribs hanging nearly vertical.
• ConfirmedThe spine slopes down toward the front and drops low near the neck; the lungs fill the chest up to the ribs on either side of it, with no empty space between. National Deer Association, Dr. Grant Woods.
• ConfirmedThe shoulder blade points forward and down, the upper leg bone angles back, and the gap between them holds no bone but ribs. Outdoor Life, onX deer shot placement.
• CorrectedOn elk the shoulder blade now sits further back over the chest than on deer, and the text notes it is much heavier. onX elk shot placement.
• Not verifiedThe number of sacral vertebrae (sources give 4 or 5) and the exact shape of each bone.

Heart, lungs and vessels

• CorrectedHeart moved forward and made smaller: in line with the middle of the front leg, top at the midpoint between back and belly, about 4 inches tall in a whitetail. onX deer shot placement. On elk: low, roughly centred under the front leg. onX elk.
• ConfirmedIn ruminants the heart lies between the 3rd and 6th ribs. Keele University ruminant topography lecture notes (Studocu copy).
• ConfirmedLungs are tallest and widest at the shoulder crease, narrow toward the front, and taper to a higher, thinner target at the rear. Outdoor Life, National Deer Association.
• ConfirmedThe aorta runs under the backbone from the heart toward the hips; carotid arteries in the neck; femoral arteries in the hindquarters. Bowhunters United (a hunting publication; no veterinary source was checked for this).
• Not verifiedWhich rib the rear edge of the lungs reaches, the size of an elk's heart, and the exact course of the vena cava.

Belly organs

• ConfirmedThe rumen fills most of the left side of the belly. WikiVet, University of Minnesota ungulate anatomy guide.
• CorrectedLiver moved almost entirely to the right side, where the stomach pushes it in ruminants; it lies between the lungs and stomach, right behind the diaphragm. Veterinary teaching material for cattle (University of Minnesota, Keele lecture notes), onX deer.
• CorrectedLeft kidney moved back and toward the midline, where the rumen pushes it in ruminants; right kidney moved forward under the last rib. University of Minnesota, IMAIOS vet-Anatomy, goat kidney CT study. These describe cattle and goats; no deer-specific source was found, and the shift is smaller in small ruminants.
• Not verifiedThe exact shape and position of the intestines, colon and bladder beyond their general region.

Head

• CorrectedA whitetail's brain is about 3 inches across, up to 4 in a large buck, and sits above the line between the eyes. Outdoor Life.
• Not verifiedThe size of an elk's brain.

Body sizes

• ConfirmedBull elk about 700 lb, 5 ft at the shoulder, 8 ft nose to tail. CorrectedCow elk shortened to about 6½ ft nose to tail (about 500 lb, 4½ ft). Rocky Mountain Elk Foundation, National Park Service, Washington Dept. of Fish & Wildlife.
• CorrectedWhitetail figures lowered: bucks average about 120–160 lb and does 80–130 lb, about 3 ft at the shoulder. Pennsylvania Game Commission, MassWildlife, Virginia DWR.
• CorrectedHeart-lung zone: about 8–10 in on a whitetail. For elk, guides disagree, from 12–15 in up to 18–24 in for a broadside bull, so the app now shows that range. onX, Grand View Outdoors, American Hunter.

Shot placement and tracking

• ConfirmedBroadside hold: follow the front leg up, a third to halfway up the chest. Quartering away: aim to exit the far shoulder. Quartering toward: rifle only, into the near shoulder. Treestand: hold higher on the near side. Outdoor Life, onX elk.
• CorrectedDouble-lung or heart: animals usually go down within about 100–150 yards; wait at least 30 minutes. ilearntohunt, onX elk.
• ConfirmedLiver: wait 4–6 hours (one source says 6–8). Gut: wait 8–12 hours or overnight (one biologist says at least 12). ilearntohunt, onX deer, Buckmasters.
• CorrectedSingle lung: sources disagree, from 2–4 hours to 8–10 hours, so the app now gives that range. Bowhunters United, MeatEater, onX.
• ConfirmedUphill and downhill: a bullet strikes high on a steep angle in either direction, so hold for the level (horizontal) distance, not the straight-line range; under about 100 yards the effect is small. Rifleman's rule, NSSF Let's Go Shooting, Sporting Shooter.
• Not verifiedUphill hold: the advice to hold lower on the near side is the mirror image of the sourced treestand advice; no source was found that states it directly. The app's suggested hold is computed from the model's geometry for any angle.
• ConfirmedHead and neck shots: tiny target, often wound or paralyse. Outdoor Life.
• Not verifiedWait times specific to elk (the deer figures are used for both), and the kidney-hit guidance. Wait times are conventions from hunting publications, not measured data.

Field dressing

• ConfirmedApproach from behind, watch the chest, touch the eye with a stick, then tag. Hunter-Ed: approaching downed game.
• ConfirmedGloves; blade up with two fingers guarding the stomach; cut around and tie off the anus; cut windpipe and gullet high and pull; cut the diaphragm; do not rupture the bladder; prop the cavity open. Hunter-Ed: field dressing larger game, North Carolina Wildlife Resources Commission.
• CorrectedCooling: get the carcass to 40 °F or below as soon as possible; wipe the cavity rather than rinsing it. Michigan State University Extension, Penn State Extension, NC Wildlife.
• ConfirmedChronic wasting disease: avoid cutting through the brain or spinal column, and bone out the meat. Missouri Dept. of Health, Idaho Fish and Game.
• ConfirmedGutless method takes the quarters and backstraps without opening the body cavity. Rocky Mountain Elk Foundation.
• CorrectedTwo claims were removed because no source was found: that the tenderloins can be reached from behind the last rib without gutting, and that an elk's breastbone must be split to reach the windpipe.