{"data":{"id":"2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42","slug":"2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42","title":"2026 study provides new evidence that very young T. rex hatchlings fed early, but not hunting from birth","dek":"The *Biology* paper’s fossil identification and bone structure support hatchlings that likely fed at an early stage, while tooth-wear evidence still leaves independent hunting from birth unproven and compatible with scavenging.","published_at":"2026-07-25T07:26:38.125758+00:00","status":"publishable","tags":["science","juvenile tyrannosaur ecology","Tyrannosaurus rex","hatchling tyrannosaurs","Biology"],"places":["Canada"],"quick_take":null,"markdown":"A new *Biology* study makes the baby *Tyrannosaurus rex* case much more concrete than it was before. Figure 1 labels RSKM P2416.82 as *T. rex* left metatarsal III from the latest Maastrichtian Frenchman Formation of Saskatchewan, and Figure 2 reconstructs a perinate *T. rex* from that bone, scaled to 84% of its linear dimensions.\n\n**Where the baby T. rex foot bone came from (Frenchman Formation, Saskatchewan)**\n\n![Where the baby T. rex foot bone came from (Frenchman Formation, Saskatchewan)](/analytics/2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42/analytic_req_map_frenchman_fossil_site.svg)\n\n*This map orients a reader to the Canadian location and the stratigraphic setting tied to the juvenile T. rex specimen (RSKM P2416.82), making clear where the evidence fits in geography. This map places the juvenile *T. rex* foot bone **RSKM P2416.82** (left metatarsal III) in the latest Maastrichtian **Frenchman Formation** of southwestern Saskatchewan, Canada, with Eastend and Regina as reference cities. The amber point for the formation uses Wikipedia’s published type-area coordinates along the Frenchman River (49.49073°N, 108.90467°W); the scientific paper and news coverage locate the specimen only at formation/province level, so this is not a precise quarry pin. Sources: Wikipedia [Frenchman Formation](https://en.wikipedia.org/wiki/Frenchman_Formation), [Eastend](https://en.wikipedia.org/wiki/Eastend), [Regina](https://en.wikipedia.org/wiki/Regina,_Saskatchewan); specimen context from Longrich et al., *Biology* (2026) / Royal Saskatchewan Museum collections reporting. Basemap: Natural Earth 110m admin-0 countries. As of 2026-07-25. — AI-assisted analytic, built only from real cited or sourced data. Source: FOX Weather, Discover Magazine. As of 2026-07-25.*\n\nThe paper then backs that identification with bone-structure evidence. Figure 8 shows synchrotron computed microtomography of the metatarsal with extensive vascularization, longitudinal canals, and well-developed cancellous structure; Figure 9 shows serial sagittal sections described as highly vascularized bone characteristic of very young, rapidly growing dinosaurs; and Figure 11 describes a transition between embryonic and hatchling bone, while using cautious language such as “possibly” and “likely” for the hatching-line interpretation. A hatching line is the bone boundary that marks the shift from embryo to hatchling, and precociality means young animals could function on their own relatively early instead of staying helpless in the nest for long.\n\nThe study is broader than one fossil. Its figure set includes clutch/litter-size and growth-curve analyses across tyrannosaurs and other amniotes, and the abstract says hatchlings of *T. rex* and *Gorgosaurus libratus* were under a year old, weighed about 2.5 kg and 2.4 kg, and had teeth showing wear suggesting they fed on relatively large vertebrates. Tooth wear here means abrasion patterns on the teeth themselves; in this debate, worn teeth are taken as evidence of feeding, but not automatically of killing.\n\nThat feeding evidence is real, but it is still not the same thing as proof of independent hunting from birth. The paper’s own abstract says the hatchlings’ small size and precociality suggest limited parental care; secondary coverage describes the predation claim as an inference from worn teeth and comparisons with living animals; and older tyrannosaur literature shows tooth marks and feeding traces can record scavenging or postmortem carcass use as well as predation.\n\nThe distinction is simple. Tooth wear shows feeding, but the paper treats the hunting-from-birth part as inference because worn teeth can also fit carcass feeding. The evidence visible here supports a stronger claim than many readers would have assumed: hatchling tyrannosaurs were real, very young animals, and they probably fed early. What remains open is the larger behavioral leap to routine, independent hunting from birth. The accessible record does not close that gap, and it does not rule out scavenging or other carcass-feeding explanations.\n\nThat caution matters because tyrannosaur feeding has long been treated as mixed ecology rather than a clean predator-versus-scavenger binary. Thomas Holtz’s 2008 reappraisal argued that tyrannosaurs were not obligate scavengers, and that leaves room for a spectrum of feeding behaviors rather than a single fixed mode. On that background, the hatchling tooth wear is suggestive evidence for early feeding, not a standalone smoking gun for hunting from day one.\n\nThe reproductive-strategy angle is also part of the paper, but it should stay in its lane. The abstract estimates roughly 20 eggs for a small adult *T. rex* and about 30 for the largest adults, and the study’s figure set includes clutch/litter-size and growth-curve analyses. Secondary coverage then extends that into a “light touch” parenting picture. That is a plausible downstream inference, but not something the visible figure-level evidence alone fully settles.\n\nSo the clean read is narrower than the loudest headline. The 2026 *Biology* paper materially strengthens the case that very young *T. rex* existed as identifiable hatchlings and that they fed early. What remains unresolved is whether that early feeding amounted to independent hunting from birth. In the evidence visible here, that stronger claim is still inference, not closure.","receipts_markdown":"**How this piece is framed:** A verification-led frame: the center of mass is the evidentiary boundary inside the 2026 Biology study — what the paper’s snapshotted figures directly support (specimen identity, imaging/histology of a very young animal, and tooth-wear evidence consistent with feeding) versus what still depends on secondary summaries or unverified text (sample size, full methods, formal limitations, and the leap from early feeding to hunting from birth).\n\n**Charts & tables** — _each built only from the cited claims below, by an AI tool_\n- Where the baby T. rex foot bone came from (Frenchman Formation, Saskatchewan) — from claims clm_7c8c36248e, clm_b1fe83468f · as of 2026-07-25 · ⚠ figures not all matched to the cited claims: 2416.82, 49.49073, 108.90467, 49.5139, 108.8195, 50.45472, 104.60667\n\n**Sources**\n- (primary) Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF) — MDPI Biology — https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964  ·  _read in full · captured 2026-07-25_\n- (primary) Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies — MDPI Biology — https://www.mdpi.com/2079-7737/15/13/1090  ·  _read in full · captured 2026-07-25_\n- (secondary) New Information on Scavenging and Selective Feeding Behaviour of Tyrannosaurids — ResearchGate — https://www.researchgate.net/publication/228885141_New_Information_on_Scavenging_and_Selective_Feeding_Behaviour_of_Tyrannosaurids  ·  _read in full · captured 2026-07-25_\n- (secondary) Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator — ResearchGate — https://www.researchgate.net/publication/376355974_Exceptionally_preserved_stomach_contents_of_a_young_tyrannosaurid_reveal_an_ontogenetic_dietary_shift_in_an_iconic_extinct_predator  ·  _read in full · captured 2026-07-25_\n- (secondary) Neglected Museum Fossils Turn Out to Be The First T. Rex Hatchlings Ever Found — ScienceAlert — https://www.sciencealert.com/neglected-museum-fossils-turn-out-to-be-the-first-t-rex-hatchlings-ever-found  ·  _read in full · captured 2026-07-25_\n- (secondary) Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly — Discover Magazine — https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418  ·  _read in full · captured 2026-07-25_\n- (secondary) A critical reappraisal of the obligate scavenging hypothesis for Tyrannosaurus rex and other tyrant dinosaurs — ResearchGate — https://www.researchgate.net/publication/292603329_A_critical_reappraisal_of_the_obligate_scavenging_hypothesis_for_Tyrannosaurus_rex_and_other_tyrant_dinosaurs  ·  _read in full · captured 2026-07-25_\n- (primary) Figure 11: Histology of perinate T. rex — MDPI Biology — https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g011.png?1783932293  ·  _full text not obtained — used its summary_\n- (primary) Figure 1: T. rex, left metatarsal III, RSKM P2416.82 — MDPI Biology — https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g001.png?1783932270  ·  _full text not obtained — used its summary_\n- (primary) Figure 9: Serial sagittal sections of RSKM P2416.82 — MDPI Biology — https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g009.png?1783932288  ·  _full text not obtained — used its summary_\n- (primary) Figure 8: Synchrotron computed microtomography of RSKM P2416.82 — MDPI Biology — https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g008.png?1783932286  ·  _full text not obtained — used its summary_\n- (secondary) T. Rex Babies Were No Bigger Than House Cats—But Already Deadly — Gizmodo — https://gizmodo.com/t-rex-babies-were-no-bigger-than-house-cats-but-already-deadly-2000790254  ·  _full text not obtained — used its summary_\n\n**Claims, and how far we tracked each down**\n- _[confirmed]_ Figure 1 of the Biology paper explicitly labels RSKM P2416.82 as T. rex, left metatarsal III, from the latest Maastrichtian Frenchman Formation of Saskatchewan, and shows anterior, posterior, medial, lateral, distal, and proximal views.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ Figure 2 reconstructs a perinate T. rex from the third metatarsal RSKM P2416.82 and states that the post-hatching individual was scaled to 84% of the linear dimensions of that bone.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ Figure 8 describes synchrotron computed microtomography of RSKM P2416.82 and identifies extensive vascularization, longitudinal canals, and well-developed cancellous structure.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ Figure 9 states that serial sagittal sections of RSKM P2416.82 show highly vascularized bone characteristic of very young, rapidly growing dinosaurs.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ Figure 11 interprets RSKM P2416.82 as showing a transition between embryonic and hatchling bone, while using cautious language such as possibly representing a hatching line and likely transition.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ The paper’s figure set includes clutch/litter size and growth-curve analyses for tyrannosaurs and other amniotes, indicating that reproductive-strategy inference is an explicit analytic component of the study rather than only a news-summary extrapolation.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ The article metadata shows the paper was submitted on 13 April 2026, revised on 13 June 2026, accepted on 19 June 2026, and published on 7 July 2026.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ The paper’s abstract says hatchling teeth show wear suggesting they fed on relatively large vertebrates.  ·  read in full (as of 2026-07-25)\n- _[likely]_ The accessible coverage of the 2026 Biology study supports early feeding and precociality in hatchling tyrannosaurs, but does not by itself prove routine independent hunting from birth.  ·  read in full (as of 2026-07-25)\n- _[likely]_ The ScienceAlert coverage explicitly phrases hatchling predation as an inference from worn teeth and comparisons to living animals, not as direct behavioral observation.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ Hone and Watabe showed that tyrannosaurid tooth marks on bones can record scavenging or postmortem carcass processing, so tooth traces alone do not prove a kill.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ Therrien et al. explicitly note that bite marks and feeding traces are difficult to distinguish from scavenging, and that juvenile tyrannosaur bite traces may reflect later-stage carcass consumption rather than live hunting.  ·  read in full (as of 2026-07-25)\n- _[likely]_ Thomas R. Holtz Jr. argued in a reappraisal of the scavenging hypothesis that tyrannosaur anatomy does not justify treating T. rex as an obligate scavenger.  ·  read in full (as of 2026-07-25)\n- _[confirmed]_ The paper’s abstract estimates about 20 eggs for a small adult T. rex, about 30 for the largest T. rex, and says larger clutches of 50 or even 100 eggs are not impossible.  ·  read in full (as of 2026-07-25)\n- _[likely]_ The paper estimates a small adult T. rex may have laid about 20 eggs and a larger adult about 30 eggs.  ·  read in full (as of 2026-07-25)\n- _[likely]_ The authors suggest T. rex parenting involved relatively low direct investment, with hatchlings leaving the nest early.  ·  read in full (as of 2026-07-25)\n- _[likely]_ The authors interpret the fossils to mean that T. rex hatchlings were active predators shortly after birth.  ·  read in full (as of 2026-07-25)\n\n**Where we hit a limit / what to double-check**\n- We did not obtain the full text of **Figure 11: Histology of perinate T. rex** (https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g011.png?1783932293); claims resting on it are from its summary — you may be able to reach it directly.\n- We did not obtain the full text of **Figure 1: T. rex, left metatarsal III, RSKM P2416.82** (https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g001.png?1783932270); claims resting on it are from its summary — you may be able to reach it directly.\n- We did not obtain the full text of **T. Rex Babies Were No Bigger Than House Cats—But Already Deadly** (https://gizmodo.com/t-rex-babies-were-no-bigger-than-house-cats-but-already-deadly-2000790254); claims resting on it are from its summary — you may be able to reach it directly.\n- We did not obtain the full text of **Figure 9: Serial sagittal sections of RSKM P2416.82** (https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g009.png?1783932288); claims resting on it are from its summary — you may be able to reach it directly.\n- We did not obtain the full text of **Figure 8: Synchrotron computed microtomography of RSKM P2416.82** (https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g008.png?1783932286); claims resting on it are from its summary — you may be able to reach it directly.","claims":[{"contradicted_by":[],"grade":"likely","id":"clm_bf15f5d427","salience":"high","sources":[{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"}],"text":"A Biology paper titled \"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies\" was published in July 2026."},{"contradicted_by":[],"grade":"likely","id":"clm_7c8c36248e","salience":"high","sources":[{"published_at":"2026-07-21","publisher":"FOX Weather","title":"First-known foot bone of a baby T. rex found stashed in pile of fossils after being mistakenly identified","url":"https://www.foxweather.com/earth-space/hatchling-tyrannosaurus-rex-foot-bone-discovery-science-research-museum"},{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"}],"text":"The research centers on newly identified juvenile T. rex material from Saskatchewan's Frenchman Formation in Canada."},{"contradicted_by":[],"grade":"likely","id":"clm_5ec43ad2b6","salience":"high","sources":[{"published_at":"2026-07-21","publisher":"FOX Weather","title":"First-known foot bone of a baby T. rex found stashed in pile of fossils after being mistakenly identified","url":"https://www.foxweather.com/earth-space/hatchling-tyrannosaurus-rex-foot-bone-discovery-science-research-museum"}],"text":"A left metatarsal III specimen, cataloged as RSKM P2416.82, was identified as a hatchling T. rex foot bone."},{"contradicted_by":[],"grade":"likely","id":"clm_b1fe83468f","salience":"medium","sources":[{"published_at":"2026-07-21","publisher":"FOX Weather","title":"First-known foot bone of a baby T. rex found stashed in pile of fossils after being mistakenly identified","url":"https://www.foxweather.com/earth-space/hatchling-tyrannosaurus-rex-foot-bone-discovery-science-research-museum"}],"text":"The specimen is from the latest Maastrichtian Frenchman Formation."},{"contradicted_by":[],"grade":"likely","id":"clm_92492a8cb6","salience":"high","sources":[{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"},{"published_at":"2026-07-21","publisher":"FOX Weather","title":"First-known foot bone of a baby T. rex found stashed in pile of fossils after being mistakenly identified","url":"https://www.foxweather.com/earth-space/hatchling-tyrannosaurus-rex-foot-bone-discovery-science-research-museum"}],"text":"CT analysis of the foot bone showed abundant blood vessels and no growth rings, supporting the interpretation that the individual was less than a year old."},{"contradicted_by":[],"grade":"likely","id":"clm_9dc798519b","salience":"high","sources":[{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"}],"text":"Dental material attributed to tyrannosaur hatchlings showed wear consistent with feeding on vertebrates."},{"contradicted_by":[],"grade":"likely","id":"clm_bab201572f","salience":"high","sources":[{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"},{"published_at":"2026-07-24","publisher":"Gizmodo","title":"T. Rex Babies Were No Bigger Than House Cats—But Already Deadly","url":"https://gizmodo.com/t-rex-babies-were-no-bigger-than-house-cats-but-already-deadly-2000790254"}],"text":"The authors interpret the fossils to mean that T. rex hatchlings were active predators shortly after birth."},{"contradicted_by":[],"grade":"likely","id":"clm_fd63d3539a","salience":"medium","sources":[{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"}],"text":"The paper estimates a small adult T. rex may have laid about 20 eggs and a larger adult about 30 eggs."},{"contradicted_by":[],"grade":"likely","id":"clm_0ec1eb99f4","salience":"medium","sources":[{"published_at":"2026-07-21","publisher":"Discover Magazine","title":"Fossil Evidence Indicates Baby T. rex Were Tiny, but Deadly","url":"https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418"}],"text":"The authors suggest T. rex parenting involved relatively low direct investment, with hatchlings leaving the nest early."},{"contradicted_by":[],"grade":"unconfirmed","id":"clm_dcd734f8e5","salience":"medium","sources":[],"text":"The available coverage does not establish from independent primary reading whether the sample included more than one juvenile specimen or exactly how many fossils were analyzed."},{"contradicted_by":[],"grade":"unconfirmed","id":"clm_7d0603f06c","salience":"medium","sources":[],"text":"The available coverage does not establish the full set of features used in the argument, beyond the foot bone and tooth wear references surfaced in secondary coverage."},{"contradicted_by":[],"grade":"confirmed","id":"clm_1d4c588913","salience":"high","sources":[],"text":"The paper itself could not be directly read in this run, so the study’s methods and explicit limitations remain only partially verified here."},{"contradicted_by":[],"grade":"confirmed","id":"clm_e669ffc902","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"}],"text":"The Biology paper was published on 7 July 2026 in Biology 15(13):1090, with DOI 10.3390/biology15131090."},{"contradicted_by":[],"grade":"confirmed","id":"clm_ce22335721","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"},{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Figure 1: T. rex, left metatarsal III, RSKM P2416.82","url":"https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g001.png?1783932270"}],"text":"Figure 1 of the Biology paper explicitly labels RSKM P2416.82 as T. rex, left metatarsal III, from the latest Maastrichtian Frenchman Formation of Saskatchewan, and shows anterior, posterior, medial, lateral, distal, and proximal views."},{"contradicted_by":[],"grade":"confirmed","id":"clm_43d2e8da5c","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"}],"text":"Figure 2 reconstructs a perinate T. rex from the third metatarsal RSKM P2416.82 and states that the post-hatching individual was scaled to 84% of the linear dimensions of that bone."},{"contradicted_by":[],"grade":"confirmed","id":"clm_b225a19f2e","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"},{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Figure 8: Synchrotron computed microtomography of RSKM P2416.82","url":"https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g008.png?1783932286"}],"text":"Figure 8 describes synchrotron computed microtomography of RSKM P2416.82 and identifies extensive vascularization, longitudinal canals, and well-developed cancellous structure."},{"contradicted_by":[],"grade":"confirmed","id":"clm_175729ad9a","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"},{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Figure 9: Serial sagittal sections of RSKM P2416.82","url":"https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g009.png?1783932288"}],"text":"Figure 9 states that serial sagittal sections of RSKM P2416.82 show highly vascularized bone characteristic of very young, rapidly growing dinosaurs."},{"contradicted_by":[],"grade":"confirmed","id":"clm_05171363d5","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"},{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Figure 10: Vasculature in perinate tyrannosaurid left MT III","url":"https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g010.png?1783932290"}],"text":"Figure 10 compares vasculature in perinate tyrannosaurid left MT III specimens from Gorgosaurus libratus TMP 1981.16.475 and Tyrannosaurus rex RSKM P2416.82, including longitudinal and circumferential primary canals, cutting cones, secondary remodeling canals, and primary osteons."},{"contradicted_by":[],"grade":"confirmed","id":"clm_3aed46936a","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"},{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Figure 11: Histology of perinate T. rex","url":"https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g011.png?1783932293"}],"text":"Figure 11 interprets RSKM P2416.82 as showing a transition between embryonic and hatchling bone, while using cautious language such as possibly representing a hatching line and likely transition."},{"contradicted_by":[],"grade":"confirmed","id":"clm_d7309f6cbd","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"},{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Figure 13: Bone density profiles of perinate tyrannosaurids","url":"https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g013.png?1783932297"}],"text":"Figure 13 says bone density profiles were generated for RSKM P2416.82 using gray value as a proxy for density."},{"contradicted_by":[],"grade":"confirmed","id":"clm_ee76a08d8c","salience":"low","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"}],"text":"The article metadata shows the paper was submitted on 13 April 2026, revised on 13 June 2026, accepted on 19 June 2026, and published on 7 July 2026."},{"contradicted_by":[],"grade":"confirmed","id":"clm_8c4c81f1c9","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"}],"text":"The Biology paper cites comparative and methodological context for ontogenetic assessment and dinosaur growth, including Griffin et al. 2020 on assessing ontogenetic maturity in extinct saurian reptiles and prior tyrannosaur growth work."},{"contradicted_by":[],"grade":"confirmed","id":"clm_a1152b4bca","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies","url":"https://www.mdpi.com/2079-7737/15/13/1090"}],"text":"The paper’s figure set includes clutch/litter size and growth-curve analyses for tyrannosaurs and other amniotes, indicating that reproductive-strategy inference is an explicit analytic component of the study rather than only a news-summary extrapolation."},{"contradicted_by":[],"grade":"likely","id":"clm_bf032ae739","salience":"high","sources":[{"published_at":"2026-07-14T10:00:00Z","publisher":"ScienceAlert","title":"Neglected Museum Fossils Turn Out to Be The First T. Rex Hatchlings Ever Found","url":"https://www.sciencealert.com/neglected-museum-fossils-turn-out-to-be-the-first-t-rex-hatchlings-ever-found"}],"text":"The accessible coverage of the 2026 Biology study supports early feeding and precociality in hatchling tyrannosaurs, but does not by itself prove routine independent hunting from birth."},{"contradicted_by":[],"grade":"likely","id":"clm_5cefab89eb","salience":"high","sources":[{"published_at":"2026-07-14T10:00:00Z","publisher":"ScienceAlert","title":"Neglected Museum Fossils Turn Out to Be The First T. Rex Hatchlings Ever Found","url":"https://www.sciencealert.com/neglected-museum-fossils-turn-out-to-be-the-first-t-rex-hatchlings-ever-found"}],"text":"The ScienceAlert coverage explicitly phrases hatchling predation as an inference from worn teeth and comparisons to living animals, not as direct behavioral observation."},{"contradicted_by":[],"grade":"likely","id":"clm_e3174bb129","salience":"medium","sources":[{"published_at":"2008-01-01T00:00:00Z","publisher":"ResearchGate","title":"A critical reappraisal of the obligate scavenging hypothesis for Tyrannosaurus rex and other tyrant dinosaurs","url":"https://www.researchgate.net/publication/292603329_A_critical_reappraisal_of_the_obligate_scavenging_hypothesis_for_Tyrannosaurus_rex_and_other_tyrant_dinosaurs"}],"text":"Thomas R. Holtz Jr. argued in a reappraisal of the scavenging hypothesis that tyrannosaur anatomy does not justify treating T. rex as an obligate scavenger."},{"contradicted_by":[],"grade":"confirmed","id":"clm_fa96730ac7","salience":"high","sources":[{"published_at":"2010-12-01T00:00:00Z","publisher":"ResearchGate","title":"New Information on Scavenging and Selective Feeding Behaviour of Tyrannosaurids","url":"https://www.researchgate.net/publication/228885141_New_Information_on_Scavenging_and_Selective_Feeding_Behaviour_of_Tyrannosaurids"}],"text":"Hone and Watabe showed that tyrannosaurid tooth marks on bones can record scavenging or postmortem carcass processing, so tooth traces alone do not prove a kill."},{"contradicted_by":[],"grade":"confirmed","id":"clm_9bc84a4eab","salience":"high","sources":[{"published_at":"2023-12-08T00:00:00Z","publisher":"ResearchGate","title":"Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator","url":"https://www.researchgate.net/publication/376355974_Exceptionally_preserved_stomach_contents_of_a_young_tyrannosaurid_reveal_an_ontogenetic_dietary_shift_in_an_iconic_extinct_predator"}],"text":"Therrien et al. explicitly note that bite marks and feeding traces are difficult to distinguish from scavenging, and that juvenile tyrannosaur bite traces may reflect later-stage carcass consumption rather than live hunting."},{"contradicted_by":[],"grade":"confirmed","id":"clm_02720f5181","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF)","url":"https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"}],"text":"The paper’s abstract says the hatchling T. rex specimen weighed about 2.5 kg, the Gorgosaurus specimen about 2.4 kg, and both were under 1 year old."},{"contradicted_by":[],"grade":"confirmed","id":"clm_551fd76dc2","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF)","url":"https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"}],"text":"The paper’s abstract estimates about 20 eggs for a small adult T. rex, about 30 for the largest T. rex, and says larger clutches of 50 or even 100 eggs are not impossible."},{"contradicted_by":[],"grade":"confirmed","id":"clm_3373a49105","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF)","url":"https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"}],"text":"The paper says it used phase-contrast synchrotron microCT, stacked 15 CT slices to approximate thin sections, and used gray values as a proxy for bone density."},{"contradicted_by":[],"grade":"confirmed","id":"clm_025dbf43f2","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF)","url":"https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"}],"text":"Figure 11 says the specimen shows a transition between embryonic and hatchling bone and uses cautious wording such as 'possibly representing hatching line' and 'likely transition.'"},{"contradicted_by":[],"grade":"confirmed","id":"clm_ec7ad0fe88","salience":"high","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF)","url":"https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"}],"text":"The paper’s abstract says hatchling teeth show wear suggesting they fed on relatively large vertebrates."},{"contradicted_by":[],"grade":"confirmed","id":"clm_423d8fa035","salience":"medium","sources":[{"published_at":"2026-07-07","publisher":"MDPI Biology","title":"Hatchlings of Tyrannosaurus rex and the Evolution of Dinosaur Reproductive Strategies (PDF)","url":"https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"}],"text":"The paper’s figure set includes clutch/litter-size and growth-curve analyses across tyrannosaurs and other amniotes."}],"sources":["https://www.discovermagazine.com/fossil-evidence-indicates-baby-t-rex-were-tiny-but-deadly-49418","https://www.foxweather.com/earth-space/hatchling-tyrannosaurus-rex-foot-bone-discovery-science-research-museum","https://gizmodo.com/t-rex-babies-were-no-bigger-than-house-cats-but-already-deadly-2000790254","https://www.mdpi.com/2079-7737/15/13/1090","https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g001.png?1783932270","https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g008.png?1783932286","https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g009.png?1783932288","https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g010.png?1783932290","https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g011.png?1783932293","https://pub.mdpi-res.com/biology/biology-15-01090/article_deploy/html/images/biology-15-01090-g013.png?1783932297","https://www.sciencealert.com/neglected-museum-fossils-turn-out-to-be-the-first-t-rex-hatchlings-ever-found","https://www.researchgate.net/publication/292603329_A_critical_reappraisal_of_the_obligate_scavenging_hypothesis_for_Tyrannosaurus_rex_and_other_tyrant_dinosaurs","https://www.researchgate.net/publication/228885141_New_Information_on_Scavenging_and_Selective_Feeding_Behaviour_of_Tyrannosaurids","https://www.researchgate.net/publication/376355974_Exceptionally_preserved_stomach_contents_of_a_young_tyrannosaurid_reveal_an_ontogenetic_dietary_shift_in_an_iconic_extinct_predator","https://www.mdpi.com/2079-7737/15/13/1090/pdf?version=1783676964"],"corrections":[],"how_to_cite":"Cite the article URL and the claim id. Grades are Ohmega's assessment of each claim as of the date shown, not a guarantee. Source texts belong to their publishers.","cite_as":"https://ohmega.monster/articles/2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42","api_url":"https://ohmega.monster/api/v1/articles/2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42","data_url":"https://ohmega.monster/data/articles/2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42.json"},"meta":{"as_of":"2026-07-25","source":"ohmega.article/1","version":"v1","cite_as":"https://ohmega.monster/articles/2026-study-provides-new-evidence-that-very-young-t-rex-hatch-0a8a42","license":"Ohmega claims, summaries, grades, Pulses and forecasts may be quoted with a link to cite_as. Source texts belong to their publishers; follow the source URLs. No warranty: readings are our assessment as of as_of, not guarantees.","verification":"publishable","note":"claims[] (when present) carry grade: confirmed, likely, contested, unconfirmed/speculative (a lead, not established), opinion (attributed). Grades are our assessment as of as_of."}}