694:
514:
116:
373:, however, has exceptionally long limbs with their bodies lifted high above the ground, giving them astonishing maneuverability and allowing them to truly run on all fours. True monitors are usually born with thick stripes of highly contrasting colours on their bodies, which would slowly morph into the loose speckles or stripes of an adult. The tail usually remains striped into adulthood, and many members have a long section at the end of their tails being white or lightly coloured, which is especially common in Australian species.
477:
390:
137:
377:
579:
420:, doubtlessly the largest extant lizard, has their largest known specimen measuring 3.13 m (10.3 ft) in length and, with a full stomach of food, weighs an astounding 166 kg (366 lb). Because Komodo monitors can eat up to 60% their own body weight, this weight record is considered invalid, while other specimens suggest a maximum weight range of 90 to 100 kg (200 to 220 lb). This maximum size is surpassed by large snakes like the
542:. This allows their hearts to temporarily function like a four chambered heart, which in turn ensure that oxygenated blood is quickly distributed to the body without also flooding the lungs with high-pressure blood. The highly efficient circulatory system, combined with their strong limbs, allow true monitors to become powerful sprinters. However, the primitive sprawling limbs would limit both the speed and stamina of the larger species. The
562:
356:
369:
they use to pick up scent. Like all monitors, they have slender, elongated necks. The tails are heavy and muscular, being thick at the base and laterally compressed towards the end. Most true monitors have lean bodies with long tails that can take up over half of their entire body length, but the largest species are very robust and have proportionally short tails. The
368:
True monitors are characterized by their wide skulls and strong jaws, with the nostrils cranially positioned on the sides of their snout. Their teeth are curved, serrated and concealed by thick lips, making them invisible even if their mouths are open. Their tongues are forked like a snake's, which
645:
are not considerably different compared to other predators, thus dispelling the theory that monitors kill with bacteria. It is verified that like all monitors or possibly all lizards, true monitors have special glands in their jaws, which is almost certainly a homologous feature for these reptiles.
1086:
Fry, B. G.; Wroe, S.; Teeuwisse, W.; Van Osch, M. J.; Moreno, K.; Ingle, J.; McHenry, C.; Ferrara, T.; Clausen, P.; Scheib, H.; Winter, K. L.; Greisman, L.; Roelants, K.; Van Der Weerd, L.; Clemente, C. J.; Giannakis, E.; Hodgson, W. C.; Luz, S.; Martelli, P.; Krishnasamy, K.; Kochva, E.; Kwok, H.
804:
and
Australia appeared, allowing the ancestors of today's true monitors to enter Oceania. They then produced members with colossal sizes such as early Komodo dragons and Megalania, possibly by outcompeting large local marsupial predators such as
591:
True monitors are most well known by their maximum size, but what really distinguishes them from other monitors is their great evolutionary potential to kill large prey in relation to their own body size, allowing them to occupy the niche of
646:
However, not all agree that these can be called venom glands, especially since the effect of them are too mild for prey to most lizard and especially true monitors, who often hunt prey that are simply too large to rely on venom for a kill.
428:(up to 150 kg (330 lb) in captivity), but considering that these exceptionally large specimens are reported at a much lower frequency, it is still arguable that the Komodo dragon is the largest extant squamate on Earth.
410:
ever to exist. Most species are medium-sized among monitors, with adults measuring 1 to 2 m (3 ft 3 in to 6 ft 7 in) in length and rarely exceeding weights of 10 kg (22 lb). In contrast, modern
415:
can grow to lengths of 2 m (6 ft 7 in) and, although being exceptionally lean among large lizards, still exceeds weights of over 17 kg (37 lb), easily making them the largest extant lizard in
Oceania.
1282:
554:
is significantly slower, reaching speeds of just 5–6 m/s (16–20 ft/s), although that is enough for it to chase goats and deers, which it mostly preys on. Being the largest true monitor,
742:
moved west towards West Asia and Africa, developing tall skulls and round teeth which aid in crushing shelled prey. Meanwhile, the Indo-Australian group, including subgenera
934:
Brennan, Ian G.; Lemmon, Alan R.; Lemmon, Emily
Moriarty; Portik, Daniel M.; Weijola, Valter; Welton, Luke; Donnellan, Stephen C.; Keogh, J. Scott (3 February 2020).
716:
around 20 million years ago, and the anatomy of its earliest members are thought to resemble today's Indian group, which includes modern Yellow monitors (subgenus
436:
around 50,000 years ago, measures over 5.5 m (18 ft) in length and weighs more than 575 kg (1,268 lb) according to estimates made by Wroe
526:
While most reptiles are considered to have three-chambered hearts, the hearts of true monitors – as with those of other monitors – have a well developed
768:
440:
in 2009, making it easily the largest terrestrial squamate ever. Among all the squamates, this size is only known to be surpassed by the semi-aquatic
744:
780:
738:
600:
have to prey on other lizards nearly their own size since birth, and the species adapted by developing an unusually large head-to-body ratio.
546:
is the fastest of all monitors with a recorded speed of up to 10 m/s (33 ft/s) or 36 km/h (22 mph), rivalling the aquatic
1089:"A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus"
874:"Dragon's Paradise Lost: Palaeobiogeography, Evolution and Extinction of the Largest-Ever Terrestrial Lizards (Varanidae)"
1298:"Competition and geography underlie speciation and morphological evolution in Indo-Australasian monitor lizards"
800:, are considered the closest relatives of true monitors. Around 15 million years ago, a land bridge connecting
1072:
136:
872:
Hocknull, Scott; Piper, Philip; Van den Bergh, Gert; Due, Rokus; Morwood, Michael; Kurniawan, Iwan (2009).
1039:
1267:
1262:
1025:
1004:
693:
1349:
991:"Perentie Facts: Discover The Largest Lizard In Australia (And The Fourth-Largest Lizard In The World)"
1087:
F.; Scanlon, D.; Karas, J.; Citron, D. M.; Goldstein, E. J.; McNaughtan, J. E.; Norman, J. A. (2009).
838:
1354:
498:, giving them excellent colour vision during daytime but nearly no night vision due to the lack of
774:
612:, being the most massive terrestrial reptile back then, would have competed with predators like
936:"Phylogenomics of monitor lizards and the role of competition in dictating body size disparity"
670:
935:
502:, which are vital for seeing in low-light environments. Like most lizard, true monitors are
1297:
1100:
885:
762:
535:
513:
8:
674:
567:
381:
258:
1104:
889:
1325:
1184:
1123:
1088:
951:
908:
547:
425:
344:
313:
289:
131:
1296:
Pavón-Vázquez, Carlos J.; Brennan, Ian G.; Skeels, Alexander; Keogh, J. Scott (2022).
1329:
1317:
1247:
1230:
1128:
955:
913:
797:
650:
558:
is yet slower, with its estimated top speed no more than 3 m/s (9.8 ft/s).
527:
519:
244:
1188:
873:
788:
moved east towards
Southeast Asia, quickly diversifying into a variety of different
1309:
1242:
1215:
1176:
1163:
Wood SC, Johansen K, Glass ML, Maloiy GM (1978). "Aerobic
Metabolism of the Lizard
1118:
1108:
970:
943:
903:
893:
789:
654:
400:
389:
296:
272:
265:
115:
898:
605:
584:
507:
395:
282:
251:
1216:"Komodo dragon – Smithsonian's National Zoo and Consrtvation Biology Institute"
1093:
Proceedings of the
National Academy of Sciences of the United States of America
1005:"Visual Identification Guide to the Monitor Lizard Species of the World (Genus
723:
642:
601:
593:
482:
476:
421:
417:
360:
303:
208:
947:
1343:
990:
750:
713:
682:
678:
666:
551:
465:
376:
66:
1113:
649:
True monitors live in
Australia alongside the much smaller and more diverse
1321:
1132:
917:
834:
732:
227:
1231:"Evolutionary relationships of sprint speed in Australian varanid lizards"
1146:
662:
624:
433:
41:
604:
are the only extant lizards to hunt large mammals, regularly preying on
578:
1180:
813:
807:
630:
619:
614:
495:
460:
86:
51:
1313:
801:
727:
718:
609:
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555:
503:
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455:
451:
446:
429:
412:
407:
198:
148:
124:
91:
35:
653:. Their dominance was challenged but remained stable in the face of
730:
in two directions: the Afro-Arabian group, including the subgenera
658:
641:
is a long debated topic. Experiments have shown that the saliva of
572:
543:
370:
334:
188:
168:
81:
76:
61:
56:
46:
561:
756:
708:
699:
539:
491:
355:
339:
178:
96:
71:
1283:"Are monitor lizards venomous? (the Tale of Toxicofera, part 4)"
1295:
441:
158:
871:
638:
1054:
596:
in most of their biomes. As the ruler of modern
Australia,
531:
933:
510:. They have been occasionally seen guarding their nests.
406:
True monitors gave rise to the largest known terrestrial
1085:
1228:
1162:
424:(up to 97.5 kg (215 lb) in the wild) and the
1055:"Life history and conservation of the green anaconda (
1026:"Varanus giganteus – The Monitor Lizards of the World"
1302:
Evolution; International
Journal of Organic Evolution
1147:"Observations on Parthenogenesis in Monitor Lizards"
712:
is believed to have originated in South Asia in the
309:
278:
984:
982:
980:
1263:"Komodo Dragons Kill With Venom, Researchers Find"
988:
657:. Among them, desert-dwelling true monitors (the
1341:
977:
929:
927:
1203:Lizards: Windows to the Evolution of Diversity.
1167:: Effects of Activity, Temperature, and Size".
1073:"World's longest snake captured, promptly dies"
347:, among which are the world's largest lizards.
1195:
847:Bulletin de l'Institut Botanique de Buitenzorg
1229:Clemente CJ, Thompson GG, Withers PC (2009).
924:
697:Evolutionary relationships within the genus
364:has the typical body built of a true monitor
1205:California. University of California Press.
1040:"Komodo Dragon – Species Facing Extinction"
968:
796:, with their only extant species being the
571:(4th row on the right) compared with other
114:
1246:
1122:
1112:
907:
897:
827:
685:with their populations large and stable.
634:, the largest of them that ever existed.
1156:
692:
577:
560:
512:
475:
388:
385:is the largest species of living lizards
375:
354:
538:sides of the circulatory system during
1342:
833:
343:. All of its species are found in the
989:Active Wild Admin (26 October 2018).
530:septum that completely separates the
494:that are almost entirely composed of
582:The strong skull and thick teeth of
1169:Journal of Comparative Physiology B
550:as the fastest extant reptile. The
13:
843:species from the island of Komodo"
14:
1366:
1201:Pianka, E.R., Vitt, L.J. (2003).
1052:
608:that are even heavier than them.
1248:10.1111/j.1469-7998.2009.00559.x
517:The exceptionally long limbs of
135:
39:
1289:
1275:
1255:
1222:
1208:
1139:
1079:
1065:
1046:
1032:
1018:
997:
969:Laurie Vitt (31 August 2023).
962:
865:
726:. They then spread across the
350:
1:
820:
490:True monitors have eyes with
899:10.1371/journal.pone.0007241
637:Whether true monitors carry
432:, which went extinct in the
7:
1268:National Geographic Society
688:
10:
1371:
506:, and some are capable of
471:
948:10.1101/2020.02.02.931188
677:) all remain a status of
240:
235:
132:Scientific classification
130:
122:
113:
25:
1114:10.1073/pnas.0810883106
1165:Varanus exanthematicus
703:
588:
575:
523:
487:
454:and the fully aquatic
403:
386:
365:
942:: 2020.02.02.931188.
696:
581:
564:
516:
479:
392:
379:
358:
329:, commonly known as
18:Subgenus of reptiles
1105:2009PNAS..106.8969F
890:2009PLoSO...4.7241H
671:Rosenberg's monitor
568:Varanus komodoensis
382:Varanus komodoensis
333:, is one of the 11
259:Varanus komodoensis
1235:Journal of Zoology
1181:10.1007/BF00738417
704:
589:
576:
548:leatherback turtle
524:
488:
426:reticulated python
404:
387:
366:
345:Australasian realm
314:Varanus sivalensis
290:Varanus rosenbergi
1350:Varanus subgenera
1314:10.1111/evo.14403
1099:(22): 8969–8974.
798:Crocodile monitor
565:Skull anatomy of
520:Varanus giganteus
322:
321:
245:Varanus giganteus
231:
123:Komodo dragon in
27:Varanus (Varanus)
1362:
1334:
1333:
1293:
1287:
1286:
1279:
1273:
1272:
1259:
1253:
1252:
1250:
1226:
1220:
1219:
1218:. 25 April 2016.
1212:
1206:
1199:
1193:
1192:
1160:
1154:
1153:
1151:
1143:
1137:
1136:
1126:
1116:
1083:
1077:
1076:
1075:. 12 April 2016.
1069:
1063:
1062:
1057:Eunectes murinus
1050:
1044:
1043:
1036:
1030:
1029:
1022:
1016:
1015:
1013:
1001:
995:
994:
986:
975:
974:
971:"Monitor lizard"
966:
960:
959:
931:
922:
921:
911:
901:
869:
863:
862:
860:
858:
831:
769:Phillipinosaurus
675:Spencer's goanna
655:invasive species
486:, a true monitor
401:Melbourne Museum
311:
297:Varanus spenceri
280:
273:Varanus panoptes
266:Varanus mertensi
226:
140:
139:
118:
108:
38:
31:Temporal range:
23:
22:
1370:
1369:
1365:
1364:
1363:
1361:
1360:
1359:
1355:Monitor lizards
1340:
1339:
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1294:
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1038:
1037:
1033:
1024:
1023:
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987:
978:
967:
963:
932:
925:
870:
866:
856:
854:
832:
828:
823:
691:
585:Varanus priscus
508:parthenogenesis
474:
396:Varanus priscus
353:
283:Varanus priscus
252:Varanus gouldii
225:
134:
109:
107:
106:
105:
104:
99:
94:
89:
84:
79:
74:
69:
64:
59:
54:
49:
44:
33:
32:
29:
19:
12:
11:
5:
1368:
1358:
1357:
1352:
1336:
1335:
1308:(3): 476–495.
1288:
1285:. 28 May 2020.
1274:
1271:. 18 May 2009.
1254:
1241:(4): 270–280.
1221:
1207:
1194:
1175:(4): 331–336.
1155:
1138:
1078:
1064:
1053:Rivas, Jesús.
1045:
1031:
1017:
996:
976:
961:
923:
864:
825:
824:
822:
819:
745:Euprepiosaurus
724:Bengal monitor
690:
687:
651:dwarf monitors
643:Komodo dragons
606:water buffalos
602:Komodo dragons
594:apex predators
483:Varanus varius
473:
470:
422:green anaconda
418:Komodo dragons
361:Varanus varius
352:
349:
320:
319:
318:
317:
307:
304:Varanus varius
300:
293:
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276:
269:
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55:
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40:
30:
17:
9:
6:
4:
3:
2:
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1125:
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985:
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842:
836:
835:Ouwens, P. A.
830:
826:
818:
816:
815:
810:
809:
803:
799:
795:
791:
787:
783:
782:
777:
776:
775:Solomonsaurus
771:
770:
765:
764:
759:
758:
753:
752:
751:Hapturosaurus
747:
746:
741:
740:
735:
734:
729:
725:
721:
720:
715:
714:Miocene epoch
711:
710:
702:
701:
695:
686:
684:
683:IUCN Red List
680:
679:least concern
676:
672:
668:
667:Argus monitor
664:
660:
656:
652:
647:
644:
640:
635:
633:
632:
628:and even the
627:
626:
621:
617:
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611:
607:
603:
599:
595:
587:
586:
580:
574:
570:
569:
563:
559:
557:
553:
552:Komodo dragon
549:
545:
541:
537:
533:
529:
522:
521:
515:
511:
509:
505:
501:
497:
493:
485:
484:
478:
469:
467:
466:Maastrichtian
463:
462:
457:
453:
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439:
435:
431:
427:
423:
419:
414:
409:
402:
398:
397:
391:
384:
383:
378:
374:
372:
363:
362:
357:
348:
346:
342:
341:
337:of the genus
336:
332:
331:true monitors
328:
327:
316:
315:
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306:
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298:
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53:
48:
43:
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28:
24:
21:
16:
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1301:
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1238:
1234:
1224:
1210:
1202:
1197:
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1158:
1141:
1096:
1092:
1081:
1067:
1056:
1048:
1034:
1020:
1006:
999:
964:
939:
884:(9): e7241.
881:
877:
867:
855:. Retrieved
850:
846:
840:
839:"On a large
829:
812:
806:
793:
785:
781:Soterosaurus
779:
773:
767:
761:
755:
749:
743:
739:Psammosaurus
737:
733:Polydaedalus
731:
717:
707:
705:
698:
648:
636:
629:
623:
613:
590:
583:
566:
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518:
489:
481:
459:
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437:
405:
394:
393:Skeleton of
380:
367:
359:
338:
330:
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288:
281:
271:
264:
257:
250:
243:
221:
220:
209:
26:
20:
15:
792:. Subgenus
722:) like the
663:Sand goanna
625:Procoptodon
618:to prey on
528:ventricular
434:Pleistocene
351:Description
34:3.8–0
1344:Categories
821:References
814:Thylacoleo
808:Thylacinus
794:Papusaurus
763:Papusaurus
706:The genus
631:Diprotodon
622:as big as
620:marsupials
615:Thylacoleo
496:cone cells
461:Mosasaurus
217:Subgenus:
1330:244529330
956:211297088
802:Indochina
728:Old World
719:Empagusia
610:Megalania
598:perenties
573:varanoids
556:Megalania
532:pulmonary
504:oviparous
500:rod cells
464:from the
456:mosasaurs
452:Paleocene
450:from the
447:Titanoboa
430:Megalania
413:perenties
408:squamates
335:subgenera
199:Varanidae
155:Kingdom:
149:Eukaryota
125:Indonesia
1322:34816437
1189:19320799
1133:19451641
918:19789642
878:PLOS ONE
837:(1912).
689:Taxonomy
673:and the
659:Perentie
544:perentie
536:systemic
480:Head of
458:such as
444:such as
371:perentie
236:Species
195:Family:
189:Squamata
179:Reptilia
169:Chordata
165:Phylum:
159:Animalia
145:Domain:
1124:2690028
1101:Bibcode
1007:Varanus
940:bioRxiv
909:2748693
886:Bibcode
857:6 March
841:Varanus
786:Varanus
757:Odatria
709:Varanus
700:Varanus
681:on the
540:systole
492:retinas
472:Ecology
340:Varanus
326:Varanus
222:Varanus
210:Varanus
205:Genus:
185:Order:
175:Class:
103:↓
1328:
1320:
1187:
1131:
1121:
954:
916:
906:
790:niches
669:, the
665:, the
661:, the
438:et al.
230:, 1912
228:Ouwens
1326:S2CID
1185:S2CID
1150:(PDF)
1012:(PDF)
952:S2CID
853:: 1–3
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639:toxin
442:boids
1318:PMID
1129:PMID
914:PMID
859:2017
811:and
784:and
736:and
534:and
42:PreꞒ
1310:doi
1243:doi
1239:278
1177:doi
1173:127
1119:PMC
1109:doi
1097:106
944:doi
904:PMC
894:doi
399:at
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310:†
279:†
97:N
87:K
82:J
77:T
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67:C
62:D
57:S
52:O
47:Ꞓ
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